This is what worked for me.
First, the background -
Hell (Umm..DELL) xps600
XP Media center
Pentium D 2.80
2gb ram
350gb Raid0
SB live X-gamer
SLI Geforce 7600GT OC (2)
Assorted usb drives, dvd burners
two internal dvd burners
I had the same problem as everyone else, but refused to take Dell's explanation that I needed to buy THEIR version of Vi$ta in order to make the upgrade work. Yes, they actually told me that the Retail version of Vi$ta does not come with the hardware support needed to work on the Dell system.
In a word:Bullpucky.
So I called Microsft and got the same lines others have gotten, none of which worked.
Below is the list of steps I took to get Vi$ta Ultimate installed. I have now been up and running steadily since this past Sunday.
Written steps for the upgrade to Vi$ta:
To avoid any nasty problems with the update do the following:
1.) Back up all needed non-windows os files such as documents, mp3, etc.
2.) Insert a Windows cd rom into the cdrom drive, and chose the boot from cd option either via bios, or alternate boot key option.
3.) Choose from within the Windows setup procedure, the option to first delete the partition and delete ALL partitons shown. Then format as one whole drive to NTFS format. Do NOT use Quick Format.
4.) Remove ALL usb/serial devices connected to the system and install Windows as normal.
5.) Let Windows load ONE time after the install. Do nothing as far as adding/removing hardware, drivers or software. Close any and all windows which may come up looking for drivers. As long as the box recognizes your dvd drive, you're good to go.
6.) Remove the Windows CD rom from the drive, and inset the Vi$ta 32 bit install disc. (DVD)
7.) Run the install option.
8.) An option will come up to the check for compatibility problems. Choose no. The install procedure will do this anyway, and give you a list before it installs any software.
9.) Read through the list that comes up when the compatibilty test completes. Unless it tells you outright that the upgrade will NOT work, just continue on.
10.) You will be presented with TWO upgrade types. "Upgrade" and "Clean install." Choose "Clean install" and continue. you'll be told that your old version of windows will be moved to a folder called windows.old. Following that, there will be very little if ANY further intertaction needed until the install is complete. If there is any needed, follow the onscreen prompts, which are intuitive.
11.) After the install completes, check device manager for any missing/uninstalled hardware and act accordingly.
12.) You're done. Have fun.
Jay