How big is the database?
What edition or SQL are you running ( Developer since you are running XP and Express only uses 1 Gig of RAM)?
How much RAM do you have?
Odds are the database server needs more RAM than you have available.
The Developer edition of SQL Server can only use 2 Gigs of RAM since it is for development use. To use more than 2 Gigs of rAM you’ll need to move to a server OS, and install Standard or Enterprise edition of SQL.