Cant decide which to get

CORSAIR TWINX1024-2700LL PC2700 2X512MB DDR 2-2-2 SILVER HEAT SPREADER $428.16 CAD
CORSAIR CMX512-3500C2 DDR 512MB PC3500 CAS2 32MX8 184DIMM W/ HEAT SPREADER $309.62

As far as i know the 2700LL are BH-6 and the 3500 is BH-5. I wanted the 512 of the 3500 instead of some other that is 2x256 because if i get it i want to get another 512 at a later (if they are still around). I would like to get the 2700, but if they are not going to compare to the 3500 then.....

Any info would be great

Going to use with Ultra Infinity and Mobile 2500

EDIT: I am not so sure of the TWINX1024-2700LL being BH-6 anymore

Or if you see any BH-5 or 6 here or....., this is where i will be buying

http://www.ncix.com/products/index.php?majorcatid=101&minorcatid=105