|It would help to post your complete system specs. But based on the little info you provided, you need to clean house & run as lean as possible.|
1. 509MB isn't very much RAM. You probably have 512MB with 4MB used by the onboard graphics, so not only do you have less RAM than is optimal, you have crappy/outdated graphics. Have you considered installing a real video card?
2. Norton is a resource hog. Dump it & replace it with something more lightweight. Microsoft Security Essentials or AVG Free Edition are a couple of possibilities, both are free.
3. You should have a cleaning program such as CCleaner & use it regularly.
http://www.piriform.com/ccleaner/bu... (do NOT allow Yahoo toolbar to install)
4. the less you have loading at startup, the better. I don't know what you have installed, but there's no reason for AIM, Yahoo, Google, Windows Live, Skype, iTunes, QuickTime, etc. to load & run in the background. Start them as you need them, close them when you're done with them. You can use MSCONFIG to prevent unneeded garbage from loading:
5. turn off search indexing:
6. use the minimum storage space allowable for System Restore (or disable it altogether).
7. uninstall old/unused programs.
8. empty the Recycle Bin regularly. Files in the bin still count as using drive space until the bin is emptied.
9. Defrag the hard drive regularly.
More performance tweaks can be found here: