This sometimes happens with uninstalls that involve CD/DVD burning software, such as that within OneCare for backup.
Fellow MVP, Doug Knox wrote a utility to resolve this problem for XP that also works for Vista:
http://www.dougknox.com/xp/scripts_desc/xp_cd_dvd_fix.htmpersonally, I'd not upgrade to Windows 7. I would boot from the Windows 7 DVD and wipe the hard drive by deleting the partition and then install a fresh copy of Windows 7. An upgrade can bring over all kinds of issues, while a clean install completes in about 20 minutes and brings no baggage over from Vista. An upgrade can sometimes take hours, but it is supported. An upgrade preserves programs, settings and files for the most part, while the clean instal route means you need to have your files backed up (not with OneCare since you can't restore into Win7 with OneCare) and all preograms need to be installed fresh.
Good luck.
-steve
Microsoft MVP Windows Live / Windows Live OneCare, Live Mesh, & MS Security Essentials Forums Moderator