"...you need to use a 64bit edition of Vista Premium or higher."
Most (probably all) 64-bit Linux versions will also use 4GB RAM (and higher) fully. So it's not JUST Vista. Ans so will 64-bit versions of XP. (Yes I did see you were going to use Vista anyway - just making a point!)
I would give Crucial a call or an email to ask their best recommendation. Known matched pairs are best to ensure best stability.