If you are happy with your current system, keep it. You might want to invest in one more RAM upgrade, to go for the whole gb.
In a few years it could be a very usefull file server. If not, then you can always donate.
I currently run a Barton 2500+ with 512MB memory. I have 2 200G ATA hard drives. Nothing fancy with the Video card. MB is Asus A7N8X.
Im thinking about building another machine based on Athlon 64 3800+ CPU. Asus A8N5X MB 320Gig S-ATA HD 1gig of PC3200 Mem and a 256M Asus En7300gs Video card.
Will I notice a great increase in speed?
I dont play graphic intensive games but do some online gaming and some DVD burning.