By Louis Navellier of InvestorPlace

Penny stock investing can be a great way to diversify one's portfolio during tough economic times. By adding a few aggressive, low-priced stocks you can supercharge your profits. However, penny stock investing can be very risky so I recommend finding bargain stocks with a proven track record. Namely, penny stock investments with earnings growth or strong buying pressure behind shares.

Here are seven low-priced (mostly tech) stocks that have fared very well in 2010 thus far and get my seal of approval. These aren't " penny stocks" per se, but at less than $2 a share all are very affordable and could make profitable additions to your portfolio.

Sirius XM Radio(SIRI)

Market Cap: $3.89 billion

Industry: Radio Broadcasting

Sirius XM Radio ( SIRI) is the owner of two subsidiaries: XM Satellite Radio Holdings Inc. and Satellite CD Radio Inc. The company broadcasts music, sports, news talk, entertainment, traffic and weather channels across the United States for a subscription fee. Combined, the two companies have eight in-orbit satellites and nearly 800 terrestrial repeaters. This penny stock has fared very well in 2010, and is up 67.5% year-to-date, against marginal losses by the broader markets. In its last income statement, SIRI reported revenue of $2.66 billion along with a quarterly revenue growth of 18.4% year-over-year.

Great Basin Gold (GBG)

Market Cap: $639 million

Industry: Gold

Headquartered in Vancouver, Great Basin Gold ( GBG) is engaged in the acquisition, exploration, development and trial mining of precious metals. This penny stock has recently begun exploring precious metal deposits in Tanzania and Mozambique. Since January, GBG has seen a stock increase of 10.5%, and boasts a current share price of $1.89. Analysts are estimating earnings of $0.02 this quarter, which is up from an EPS of -$0.03 a year ago.

Globalstar (GSAT)

Market Cap: $509 million

Industry: Wireless Communications

Provider of mobile voice and data communications, Globalstar ( GSAT) uses 44 in-orbit satellites and 27 ground stations to serve its customers. This wireless communications company also sells its communication services on a wholesale basis to independent companies. Since the start of 2010, GSAT stock has risen 95.4%. With a quarterly revenue growth of 2.7%, GSAT is a strong stock to buy at its current share price of $1.70.

ICO Global Communications (ICOG)

Market Cap: $375 million

Industry: Wireless Communications

Wireless telecommunication service provider ICO Global Communications ( ICOG) is a development stage mobile satellite service operator. Despite the fact that ICO has not been able to complete any additional satellites since December 2004, the penny stock has one satellite in orbit, and 10 satellites currently in the production stage. ICO has also had a very productive 2010, and is up 37% on the year, compared to small losses by the broader markets. Looking at its last 52 weeks, this penny stock has seen a major increase of 131%.

Tower Semiconductor (TSEM)

Market Cap: $308 million

Industry: Semiconductors

Tower Semiconductor ( TSEM) is an independent specialty foundry that manufactures semiconductors. This penny stock's products are used in a wide range of consumer electronics including personal computers, medical device products and automotive products. A 53.6% year-to-date climb in stock price has Tower shareholders very satisfied. Additionally, this penny stock outperformed earnings estimates by 367% last quarter, and is hoping to maintain its positive momentum this quarter.

Quest Capital (QCC)

Market Cap: $213 million

Industry: Investment Brokerage

Quest Capital ( QCC) provides real estate mortgage financing in Canada. Based in Vancouver, the majority of Quest's clients are owners of multi-unit residential buildings, land and commercial properties. Since January, this penny stock has climbed 36.6%, and is up an even 50% from last August. Quest's stock price currently sits at $1.53, and its recent performance has far outpaced the Dow Jones Industrial Average and Nasdaq, which are down 0.9% and 3.4% year-to-date, respectively.

Powerwave Technologies (PWAV)

Market Cap: $211 million

Industry: Communication Equipment

Based in Santa Ana, Calif., Powerwave Technologies ( PWAV) is a global supplier of end-to-end wireless solutions for wireless communications networks. Powerwave designs, manufactures, markets and sells products that improve coverage, capacity and data speed in wireless communication networks. Since January, this penny stock has gained nearly 30%, and has a current stock price of $1.59. Additionally, the fact that Powerwave outperformed earnings estimates by 100% last quarter makes this stock a strong buying opportunity.

As of this writing, Louis Navellier did not own a position in any of the stocks named here.

One of Wall Street's renowned growth investors, Louis Navellier is the editor of four investing newsletters: Emerging Growth (formerly known as MPT Review), Blue Chip Growth, Quantum Growth and Global Growth. His longest-running publication, Emerging Growth, has a track record of beating the market nearly 3 to 1. Navellier is the author of a BusinessWeek bestseller, "The Little Book That Makes You Rich," and the chairman and founder of Navellier & Associates, Inc.