Ballistix ram is one of the best overclocking ram available, There was another set, the yellow or normal ddr2 modules that went to on sided chips but im pretty sure the red tracers, which are newer, are back to double sided chips and they use micron d9's which are great overclocking memory chips. Definitely get your hands on them if you can, be great for your rig, i would recommend also g.skill black PI/normal PI if you can find them in uk otherwise the ballistix are just as good.
Now there is a recent thread that had an easy to understand guide for ram timings, but essentially all you need to know is that for AMD, the tighter the better. make sure you get a clk4 kit.
Crucial Ballastix RED 4GB (2x2GB) DDR2 PC2-6400C4 800MHz Dual Channel Kit : novatech.co : CRU-T644GR
there the kit i rec. you get and also heres a review stating double sided.
techPowerUp :: Crucial Ballistix Tracer Red 800 MHz 4 GB Kit Review :: Page 1 / 4
, they reached 1120mhz on clk5 at 2.2v which is great overclocking!