Here are some Crucial Ballistix RAM. These are some of the best RAM available at the moment. I appreciate that there has been some very cheap RAM on hotukdeals recently, but these should not be compared to them. This is RAM for high end systems.
Please make sure if you buy these, that your motherboard is compayible as they do require fairly high voltages.
PC2-5300 CAS3 : http://www.overclockers.co.uk/showproduct.php?prodid=MY-088-CR
PC2-6400 CAS4 : http://www.overclockers.co.uk/showproduct.php?prodid=MY-090-CR
PC2-8500 CAS5 : http://www.overclockers.co.uk/showproduct.php?prodid=MY-093-CR
Delivery is about £7 inc VAT, or can be collected for free.
£81.06 for pc2-5300
£102.21 for pc2-6400
£135.11 for pc2-8500
Id like to add finally, that even the cheapest pc2-5300 RAM can be overclocked to pc2-8500 speeds making it better than some more expensive pc2-6400 RAM. This is because they use micron D9 chips, arguably the best in the market.