Wrong operating system installed on factory repair

Hello.
I have a HP Pavilion dv2000 laptop. I sent it in for factory repair, and it was returned with a non-Vista O/S. (This is a message on the BIOS page.) It originally had Vista. I have been told by one HP tech support that (a) I must send it back in to correct this error; and by another that I can do it myself in the Systems Settings. I was unable to find this field in the BIOS page.

I'd really appreciate any info you can give me on how difficult this may be. If it's beyond the level of an average user -- or if it's something that could easily go wrong, I may opt for a second factory repair.

thanks!