NEW YORK (TheStreet) -- The worst move a rookie can make on Cyber Monday is staying on one site too long while missing better deals elsewhere. Don't be that shopper.

With Cyber Monday's popularity rivaling Black Friday's -- a survey by analytics firm Compete says 45% of shoppers have made it their holiday spending day of choice compared with 37% who favor Black Friday, while ComScore says online shoppers spent $887 million on Cyber Monday last year versus the $595 million spent online on Black Friday -- cubicle consumers can no longer count on the day's obscurity to shield them from other competitive customers.

Roughly 55% of the U.S. workforce, or 70.1 million people, will be shopping for holiday gifts from their office this year, according to the National Retail Federation, so it pays to beat them to the biggest deals. With 88% of retailers telling the NRF that they're offering Cyber Monday deals today, though, how can you tell if you're getting the best bargain?

Here are a few sale-and-price comparison sites to check out to make sure you have your bases covered before your credit card breaks a sweat. There are few things worse than loading up your cart and checking out, only to slide over to another site and see one of your wish-list items going for less. We won't let that happen:

Pricegrabber.com:

If you've got your list handy and have no problem getting 10 different items from 10 different retailers if the price is right, then Pricegrabber's just about the best way to get the best deal. Just search the item you're looking for and PriceGrabber will pull up a list comparing that item's price at

Target

(TGT) - Get Report

,

Wal-Mart

(WMT) - Get Report

,

Sears

(SHLD)

,

Amazon

(AMZN) - Get Report

,

Dell

(DELL) - Get Report

and other retailers.

Some comparisons tend to be a bit more extensive than others and some of the lowest-priced retailers can be a bit obscure, but Pricegrabber almost routinely sniffs out the lowest possible price and makes it easy to discern a genuinely good price from a great price with insanely high shipping by factoring tax and shipping information into its "bottom line" total.

Bing Shopping:

The sheer breadth of retailers whose wares are up for comparison on

Microsoft's

(MSFT) - Get Report

Bing Shopping is staggering.

Best Buy

(BBY) - Get Report

,

Barnes and Noble

(BKS) - Get Report

,

Office Depot

(ODP) - Get Report

,

Home Depot

(HD) - Get Report

,

Overstock.com

(OSTK) - Get Report

and

Macy's

(M) - Get Report

are among hundreds of retailers in Bing's database, which means lots of options once you start searching prices.

Bing Shopping also makes it really easy to discern who's offering free shipping by putting it up in big, bold type on the comparison list. Though Bing Shopping removed its cash-back incentive that may have been a bit too popular last year, the mere fact that it throws even lowball "Buy It Now" eBay items into the mix makes it a must-visit for bargain hunters.

Google Products:

Yes,

Google

(GOOG) - Get Report

Products offers great price comparisons, but it's the interface that sets it apart from the other sites. If you want to see only new products, there's a button for that. If you want to list only the retailers with free shipping, there's a button for that, too. If you want to see who's really giving you the best deal by looking at the smaller, marginalized total price rather than the big, boldface base price, a savvy shopper can sort that way as well.

Of course, because it's Google, you get Google Maps locations of online retailers' brick-and-mortar equivalents in your area, a breakdown of the best online-versus-local prices and detailed product summaries and reviews from partners including Best Buy. Seriously, they do nothing halfway.

Nextag:

Earlier this year, this site was a late-2000s mess of harsh colors, hard-to-read type and bad spreadsheet-style layouts. Now, just in time for Black Friday, Nextag has been streamlined into a sleek site with tabs on each product page for price comparisons, reviews and even a product's price history so you can see how your deal stacked up to previous years. Nextag's strength, though, has always been detail descriptions and product specs to help shoppers discern exactly what they'll be getting. While their comparisons aren't as broad as some of their competitors, the ability to sort by free shipping and customer rating makes the purchasing process a lot more clear.

CyberMonday.com:

National Retail Federation partner Shop.org doesn't just make the claim that it coined the term Cyber Monday back in 2005 -- it backs it up by loading its site of the same name with deals from 550 merchants including

Apple

(AAPL) - Get Report

,

Sony

(SNE) - Get Report

,

Staples

(SPLS)

,

Cabela's

(CAB)

,

JCPenney

(JCP) - Get Report

,

Walgreens

(WAG)

,

Nike

(NKE) - Get Report

,

Leap Frog

(LF)

and

Borders

(BGP)

.

This year, the site is running hourly flash specials by its various retail partners and allows shoppers to compare the prices of various items offered by those retailers. While the bottom-end price comparisons come in about $10 to $20 higher than what we've seen elsewhere, the lists of sales, coupons and offers by those various retailers -- free shipping and otherwise -- is unmatched anywhere else on the Web.

CyberMonday2010.com:

BradsDeals' site is similar to Shop.org's both in name and content, but the key difference is a big dip into the low end. Sure, the BradsDeals site offers deals from

HP

(HPQ) - Get Report

,

Express

(EXPR) - Get Report

and other large retailers, but its biggest strength comes from little partners like BuyDig.com, BackCountry.com and others that offer steeply slashed prices on Olympus cameras, North Face clothing and other items that look much more costly in some of the big guys' carts.

-- Written by Jason Notte in Boston.

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Jason Notte is a reporter for TheStreet.com. His writing has appeared in The New York Times, The Huffington Post, Esquire.com, Time Out New York, the Boston Herald, The Boston Phoenix, Metro newspaper and the Colorado Springs Independent.