Hey, Well, 512 will be more than enough to run your system efficiently, a gig is superb, it may be alot, then agen with a 1000m wrist watch, ur never gonna go that deep, but its good to know that you can drop it in the sink and nothing will happen.
Buy more RAM!!! I currently run Access 97 with 256MB RAM, and it's soooooooooooo slow (a large db, but still...). I'm not sure of the specs, but you're probably running on the low end of what's needed for the software you have.
Access 97 is a problem? Ha, I know. There was talk of upgrading office, but the $$$ got in the way. I believe the entire company will be getting new computers and software upgrades (about time!), but it will take about a year cuz we're a big place.