Virus killed system/Startup Repair won't fix: what's the best way to rebuild?

My kid's Vista Business 32-bit SP2 system got hit bad by a virus; when running the virus repair it removed infected system files and now he gets repeat BSODs.


No, StartUp Repair won't repair the system, and the virus seems to have killed any Restore points; also can't get SFC / SCANNOW to run successfully.


So: I went to (a huge lot of) trouble to put together a Slipstream Install DVD of Vista SP2 (since the original Install disk that came with the system was only Vista vanilla). I thought I could Load that and select the "Upgrade" option and simply rebuild the Windows system, keeping all my original programs and data.


But nooooo, after loading, the installation informed me that "Upgrade Has been Disabled", along with the clarifiying comment: "-- To upgrade, start the installation from windows" - which of course i can''t do since I can't bring the virus-corrupted system up even in Safe mode.


SO - I have a couple questions:


(1) FIRST: was my assumption right to begin with? That is, if I COULD bring up Windows on the corrupted machine (even if only in SAFE mode), would the Upgrade go ahead and work - considering that the previous virus-corrupted system was also VISTA SP2? Or - would the install inform me that it could NOT do an upgrade since it would detect that the previous version was in fact also VISTA SP2, and therefore "know" that it couldn't (truly) do an Upgrade?


(2) Assuming the answer to #1 is "yes", then: Is there any Installable version of Vista (even one I might need to purchase) that could do the upgrade even if the Windows system being upgraded cannot come up? IF NOT: How about an Upgrade installable version of Windows 7? or is it the sad fact that regardless of what version of Windows I purchase, I can't choose the "Upgrade" option unless the install is being loaded/run from Windows on the system being upgraded?


I've got all sorts of great advice from previous posts on how to go and recover the data files off of the corrupted system, so if there are no other alternatives, I'll do that - - but that's my last resort because:

(a) Its a lot of time consuming work do go extract all the files and

(b) Its even more time consuming work to then have to reload all the third party software (some of which i don't have the install disks for anymore) if I end up

having to do a clean install of Windows.


So if there are any alternatives for doing an Upgrade - even if I have to shell out some $$ for a new version of Windows, I'd rather do that.


Appreciate any advice offered - - -