Restart and tap Function 8 then select Safe Mode with Networking. That will make the system load te drivers for ethernet and, if present, wireless so you can get on the Net but the more important issue is to correct what happened.
Go from Start to Run and into the Open box, type sfc /scannow then press Enter. Have your XP CD handy in case the System File Checker asks for it to expand fresh copies of files. I don't see how you "loaded SP1 in Safe Mode" but you should update to Service Pack 3 as soon as possible, and then get about 140 subsequent updates and Hotfixes - many of which are patches for Windows security holes.