What operating system are you running? XP, Vista, or Windows 7? And are you sure it's a 1GB stick? Usually it updates the specs immediately. I guess if it's Vista or Windows 7, you might have to run the Windows Experience Index assessment again to refresh the score, but I wouldn't think it would pretend the extra memory is not there.
How many slots for RAM does the computer have and how many are filled and with what size?
You probably already have several times, but you might try rebooting the computer a time or two if you haven't. Sometimes that helps. If that doesn't do it, you might also try reseating the RAM, though I wouldn't think the computer would boot at all if the RAM was not seated properly.
(Have a look at this page for some more ideas:
http://forums.cnet.com/5208-10149_10...hreadID=194111 )
Good luck,
Brijar!!!