Hello there

I am wondering if you guys and girls would be so kind and help me at all. It's been a long time since I've been in the computer scene and i'm a little lost as to all these different chipsets and socket's for the AMD boards and CPU's. Havent even tried taking alook into Intel yet. My current system is;
AMD Athlon Barton 2500+, MSi motherboard, 512ddr, 80gig hdd running onboard GPU. I did have a geforce 3 Ti500 but that failed. I did like the reliability and options of my old Abit NF7-s board
I basically want a reasonably up to date system and have noticed the prices and advances in technology are almost unbelieveable. I tried playing a game earlier and it error'ed saying not enough system memory so it's definitly time to sort this out. I've always been an AMD man myself but I have heard of Intel being light years in front at the moment? Thing's like hyperthreading etc don't really seem to make much different for gaming?
Anyway I'm wondering if you would be able to steer me in the right direction of buying the correct motherboard chipset, CPU and GPU for light gaming needs without spending vast amounts.
Thanks in advance, gaz