Ram Recommendations

I got a basic AMD Athlon 2800+ XP system at Christmas(256Mb Ram, Onboard Graphics and Sound, 80Gig HD) and have been slowly upgrading it. I just picked up a Graphics Card for it and next i want to get some extra Ram. My Asrock K7VM4 mobo only has 2 Slots so i was thinking of putting an extra 512Mb stick in there to take it up to 768Mb. Currently i have 256Mb Kingston Ram PC2700. Can anyone recommend the best 512Mb PC2700 Ram for around £50(and maybe where to get it from). I live in the UK so will be looking to buy it here too really. Thanks.