failed upgrade to XP, now 98 won't start!

I attempted an upgrade from Windows 98 to Windows XP recently. There wasn't enough available memory to complete the upgrade, so I deleted some documents and music files to create more free space. The upgrade wouldn't work, however. Right now whenever I attempt to boot the computer up, a screen appears saying "Please select the operating system to start" and give the options of XP Setup or to cancel the XP setup. If I choose to continue setup, with the XP upgrade disk in the computer, it runs the setup program. But the installation of XP can't complete because files are missing, such as "bootvid.dll" and a whole long list of others. They can't be found for some reason. So the installation can't continue. If I exit the setup and reboot the computer to try to run Windows 98, I'm given all the options of running Windows in normal mode, safe mode, step-by-step configuration, etc. None of the options works. I'm told that the files himem.sys, dblbuff.sys, and ifshlp.sys are misisng or corrupted. What's going on and how can I fix it?

I would start by booting with the WinXP CD and seeing if anything can be done from there, such as a new instance of the update, or a repair install.

Sounds like it toasted the install of win98.
I might try rebooting ot the XP see if you can do a fresh repair install.
Its unlikely the 98 install can be recovered at all other then pulling your important files off.
I would say save the files you need to save and start with a clean install