I actually bought all the expansions sans WotLK online and the download didn't work.
Thankfully my boyfriend had the discs so I didn't need to rebuy them :U My OS is Win7 64x, I'm not sure if it's OS incompatibility stuff but I suggest so security you buy them in-person if you can :v Cause my boyfriend was charged before the download began and it didn't even work so ~___~
My Cata be on reserve at a nearby GameStop
Diablo III North America Glacea#1307
League of Legends Queen Nimera, Level 20
New Leaf/Pokemon XY 4511 - 0825 - 1589