Compaq Deskpro 2000

HI I need some help with a deskpro 2000
I can't find out which model it is. On the m/b it says 1996-1997 compaq corporation and a sticker with this no P07A1xx25FZQXA Also a sticker with a date 11/1/98.To help you identify it It has a single big slot in the centre where a riser board plugs in and other boards plug into thatThere is a no 87054 on it It has windows ME installed. The only useful thing i can find in device manager is that its a pentium but no indication of what MHZ the cpu is I wan't to load windows xp but can't get into the bios to change the boot sequence to cd rom as 1st boot device I have tried DEL,CRTL-ALT-ESC,CRTL-ALT-S,CRTL-ALT=INS,And F1 and F2 and F10 Whith no effect Every time i try i get a keyboard error I tried three different keyboards with the same result.What do you have to do to get into the bios.
Underneath the case theres a compaq label with series 3564 on it.
Can someone help me through this[/quote]