Messed up Default Operating System

I went into system startup and changed the default operating system from xp pro to xp home, but now I can't even boot up- I get "Windows could not start because of a computer disk hardware configuration problem. Could not read from the selected boot disk. Check boot path and disk hardware". This is a hand me down Dell Dimension E310, I thought maybe it had both XP pro and XP home, but home isn't booting up. It's not giving me the option to select XP pro (must not have been checked in system startup).

I know I can change the boot.ini file to go back to xp pro, but I obviously can't get there if I can't load windows. Of course I don't have a CD to boot from.

What can I do to get back to XP Pro? Should I restore BIOS defaults?

Thanks!

 

Nevermind, duh, F8 got me there. Plz delete.