i think 64 bit CPU is still not applicable because so many application are still using 32 bit. Even if there are company launch 64 bit applications, but it is still unstable and in experimental stage. Therefore, 64 bit power may not fullly utilized in recent time. It is also the reason why intel or althon not produce fully 64 bit CPU but mostly produced 32 bit CPU emulate 64 bit function.(intel Itanium is a fully 64 bit CPU, but can't compatible 32 bit application ) So i think it is unwise to using 64 bit CPU in recent time for its high price and very little in its 64 bit application,
I think one more year will be more mature for 64 bit market.