quick fix for Pci.sys error that worked for me.
Ok I also made the slipstream WinXp with service pack 2 which in my case took forever. Installed the XP with SP2 on a new hard drive since I assumed the data on my old hard drive and XP would be lost or nonfunctional.
What worked was easier than described elsewhere so here we go:
1) get a copy of windows xp with service pack 2
2) boot from the CD
3) once the blue setup screen starts choose the "repair" option instead of a new installation.
4) this will bring you to a c: prompt
5) run "chkdsk" (I can't remember if I added. the .exe ending or just typed chkdsk)
6) if no problems are found - run "fixboot"
you will be asked if you are sure you wish to do so - answer yes of course
7) Restart the computer - booting from the C: not the CD!
8) Windows should come up with different boot options - Choose "Safe Mode" not the regular boot
9) After Windows has loaded - reboot / restart once again
10) - Windows XP boots back up normally and all the programs run normally once again, and your data is still there!!!:)
11) Ta Da!
This worked for me, so I'd suggest you try this first before doing the whole windows xp reinstall (and having to reinstall all your programs again!). If it does not work for you, you can always go to plan B - a complete reinstallation of XP with a complete reinstallation of all your programs.