Try this first. If it doesn't work try slaving it to another machine and recover the files. If that doesn't work leave it in the other machine and get GetDataBack from Runtime.org.
How to do a system repair.--Boot from the xp cd and go past the recovery console to the install menu. Select repair the existing installation. You won't lose any data except the xp updates. Unless you have a slipstream sp1 cd you will have to d/l sp1 and all subsequent updates. You MUST have at least SP1 installed and the updates for security reasons. Be sure the firewall and A/V is active before going online as you will be susceptible to sasser and msblaster. If you don't want SP2 go to autopatcher.com and d/l SP1 and subsequent updates.
You can also try this. It is free.