Advanced Auto Parts ( AAP) downgraded at Credit Suisse to Neutral from Outperform based on valuation and sluggish macro environment. Lowered target price to $35 from $41. Americredit ( ACF) downgraded at FBR to an Underperform rating as December data was significantly worse than expected. Aeropostale ( ARO) downgraded at Merrill from Neutral to Sell. Company has good momentum coming out of the holidsay season, but 2008 estimates are still likely too high. Cal-Dive ( DVR) downgraded at JP Morgan from Overweight to Neutral. Estimates also cut as price competition could heat up with market saturation. Fiserv ( FISV) upgraded at Goldman Sachs. Goldman is removing the Not Rated designation from FISV and placing a Buy rating on the stock. With CheckFree acquisition and health business divestiture recently completed, see improved profit and attractive defensive play in current environment. Price target at $60. Frontier Oil ( FTO) upgraded at FBR to an Outperform rating due to expected seasonal swing as margins likely to rise. General Mills ( GIS) upgraded at JP Morgan from Underweight to Neutral. Company hosted an upbeat meeting in NY, and believe that the chances for a 2008 earnings miss are minimal. Estimates also raised, based on cost-cutting efforts. Huntington Bancshares ( HBAN) downgraded at Merrill from Neutral to Sell. Dividend will likely be at risk this year, as earnings will continue to fall. Stock still has another 16% downside potential.