best thing you can do is upgrade to 2gb ram, if your machine will allow it (is dependent on motherboard). Alternately, moving to XP will give you a big boost in responsiveness.
Norton is a big resource hog, and changing to a system like nod32 will allow your machine to work more quickly because of the reduced cpu/ram load from what norton requires.
Vista can be tweaked to work more quickly. There's a lot you can do and too much information here but if you google "vista speed tweaks" then that should get you started. If you follow this process, make sure you set system restore points as you go, so that if you get something wrong you can roll back to settings that worked.
Other basic maintenance elements also apply, such as
regular defragment
regular chkdsk
make sure always have 20% disk free space on primary drive
uninstall any software you dont use
regularly run tune-up like http://www.glaryutilities.com/gu.html
edit your startups
kill off any unnecessary processes in system tray
If you want to get really tricky you can also edit services using services.msc. I would not advise doing this unless you have done plenty of reading on what the services do and what the consequences of altering their startup parameters are likely to be.