Installing Windows...

Some one gift me a old PC Dell optiplex GX110. 7.6 GB HD, 256 Ram, P-III, 1 GHZ. Well, at some way the person did could install a Windows XP Pro copy, and when the PC try to up only appear the Win Logo and next the screen get black, appear the mouse cursor (it's possible move it) but don't do any more.
I checked the Bios set up, and the boot sequence is fine (a,cd,HD). I tried changing cd first, only hard drive, downloaded MS-DOS's Windows versions disks, but nothing happen. Only let me boot until drive a: with a start up disk, but I can change to C: or D: drive. I'll thank your help.