I used a retail CD which didn't work. The sticker says "Windows XP Professional 1-2PC". It does not specify OEM, nor does it have any additional information (aside from the PID and info about the pc). Considering it's an HP, however, I assume it is OEM. This is what I was trying to avoid doing. Haven't exactly had much luck with HP support in the past. Would rather do this than the former. I know the PC is legit, and has a legit copy of WinXP. My mother got it from a local school which had a deal with HP to give low end PC's to students taking a specific class. I've formatted/reinstalled before, but I'm pretty sure I used the CD that came with it last time..I could be mistaken. Either way, thanks for the input. If anybody else happens to know another way around it, I'd appreciate the suggestions. Not looking to circumvent the legality..it is a legit setup with a legit PID. Side question.. Would running the Recovery CD make a difference? That I do have, but it doesn't have the OS on that CD. It even specifies that I would need the Windows CD to reinstall Windows. If any additional information is needed, don't hesitate to let me know. Edit : Another thing.. If I acquired an HP OEM CD from other "sources", would that work or is each CD specific to a certain model? I'm not sure how OEM's handle that. What's the legality of that, either way, considering I have the legit PID?