Go to:
http://www.hirensbootcd.net/download.html download and mount to a cd with imgburn/nero/magicsio/ultraiso then pop it in the cdroom and boot from it.
You might need to access your bios to change the boot order, to do that, at the start, hit DEL/F1/F2/Fsomething depending on what it says on the boot up screen, then navigate to the boot options and select the CD/DVDROM as the primary, save and exit.
Then on the CD go to hard disk tools and check the S.M.A.R.T. status of your disk, if it passes you can also check using the manufacturers tools, also use the HDDRegenerator tool that comes on the CD.
Also go here:
http://oca.microsoft.com/en/windiag.asp for instructions and to download and run Microsoft memory diagnostics.
Finally if you have any additional cards (video/sound/tv) remove them and try to boot windows again to see if thats the problem.
good luck and post results.