My PC is running an amd athlon 2600+ with windows xp and 512mb of RAM and seems quite fast but would there be much advantage in upgrading the memory? I tend to do fairly undemanding taks like sound editing, surfing etc. I can go up to 2gb.
I have certainly noticed a difference - I went from 512Mb to 2Gb .... mainly to play FSX Deluxe at its higher settings - it is great! Plus some other games that are much better with the higher RAM. But apart from games, everything does run quicker. On start-up for instance, my screen with a self-taken photo as background and about 40 program icons, opens and refreshes INSTANTLY!
You wouldn't really notice much difference if you were only doing low-demanding tasks, it is when you get into some games that the difference shows. surfing and everyday jobs like emailing or using Word would not show any significant difference. Serious video work would probably benefit, though I have only done a small amount of non-serious video.