Missing Dll Files?

I had a differ video card installed which helped my pc. But some idiots decided to reload another version of xp pro. They did not use any back up program to save my files and everything they did save (which was about 60%) they loaded on to drive c: then drive d. I used to have one hard drive partioned into two. They made one big drive c:. So now to see my files - I have to go to my computer, then c: then d:. Files are in no order- program files, etc.. all mixed up in one big list.Ok smy next problem...I thought I could fix this by using my back up disks before the above people got a hold of it, well the pc took all the back up disk great, but I forgot about the d: drive no longer being there - so the disks tell me half way thru that they cannot get rights or something to d - but they do give an option to skip - which I did.. it installed the other few disks and when it said it was done, i had to reboot and i did.So.. at the end.. It boots up - but when Windows comes up - it tells me <windowsroot>system32hal.dll. is missing and to reinstall it.How do I do this? My computer is old, but it is all I got right now and I can not afford to buy anything..I will write a second post here - with my system info