GRUB error 2

Ubuntu 6.06 is installed on Dell Dimension with 2 HDs : Win XP/SP2 on primary & Ubuntu 6.06 on secondary drive. Frequently during bootup err msg "GRUB error 2, plz wait" appears. Only recovery is to re-install Ubuntu. A bug report has been filed but no action taken.

(1) how do i learn what various GRUB errs mean ?
(2) how do i uninstall 6.06 so that Win XP is only OS running ?

Thanx.
Newbie Bob