There is no upgrade path from Windows XP to Window 7. To use the Windows 7 upgrade you have to go from Vista.
I don't know if the upgrade version will have the bootloader file or not. So you do have to have a version of Windows on the computer and in this case it has to be Vista.
huh? of course you can upgrade from XP to windows 7. I did that. I never put the abomination that was Vista on my computer. What you need to do is install xp back on the Dell, possibly upgrade to SP2 or SP3, then place the Win7 upgrade disk in drive and start Win 7 upgrade process. There's a point in the Win 7 upgrade where you can choose to do a clean install (you usually will want to do this so you can install 64bit, assuming you can run 64bit).
oh i see your problem. no more dell. ok, well hopefully the sevenforums article will work for you. But if you had the dell running XP, you could upgrade to Win 7.