The shares of Dell (DELL: View sentiment for DELLsentiment, chart, options) are in for a rough start this morning. The security was downgraded by J.P. Morgan before the start of the session, moving the stock from neutral to underweight.

The brokerage firm stated that it believes investors will now begin to shift their attention to what looks to be a difficult 2007 for the company. The group warned that gross margins may disappoint in coming quarters, saying it believes any relative cost improvement that Dell achieves from Advanced Micro Devices' ( AMD: View sentiment for AMDsentiment, chart, options) recent price concessions is likely to be short lived.

Furthermore, J.P. Morgan believes Dell's enterprise business could come under pressure and the company should see little benefit from Microsoft's ( MSFT: View sentiment for MSFTsentiment, chart, options) new Vista operating system this year.

The broker stated that Dell's slanted exposure to corporate PCs suggests it will not see much benefit from Vista this year, as we don't expect Vista-driven corporate PC purchases to occur until 2008 at best.

J.P. Morgan isn't the first brokerage firm to take a bearish stance on the computer company. And probably won't be the last. According to Zacks, Dell has earned 11 buy ratings, 11 hold ratings, and just one sell rating.

In pre-market trading, the shares are poised to gap lower, as they are currently trading down roughly two percent.

In trading on Thursday, the stock staged a nice rally, pulling back above resistance at its declining 10-day and 20-day moving averages. However, with today's downgrades, the shares are likely to find themselves back below both of these resistance levels.