ok guys heres my 2 bits on this matter. my recent offline time was spent studying the differences between each release of win 7 .
MOST people don't read the fine print well enough to understand what the actual list for compatabilities.for win 7 is.
Win 7 Starter pack is simply the most basic of the newest releases of os and has very little that would be useful to a gamer. its too basic.
win 7 home is a little better than starter.. but still lacks the compatability for most of the xp games and such as we're all comfortable running.
Win 7 Professional.: NOW we're starting to talk. gaming for xp would be basic ..but here is the first of the win 7 line that actually starts with the newest feature for win7 . the xp compatability setting.
it is THIS feature you need to be able to run those kinds of games on to begin with
Win 7 Ultimate : Now HERES a Nice little package. expensive yes and muuch better than professional. its more stable

and i have the x64 bit installed myself friend.

Diablo 2 expansion is a game thats supposed to be incompatible with windows 7
BUT heres the sticker.. I can actually run it np on my win 7
yes there was a supposed compatability issue.. BUT i set my compat setting on my copy to run it as xp would..
and it runs perfectly fine.
so your game problem may actually be because youve the wrong os of win 7 installed .. unless its professional or better you WILL have the same issues as what you're faced with.
Sorry for alarming you there bud..but the compatability setting means everything.. and if you didn't get win 7 professional or better. you don't have the ability TO play xp games sorry to say ..