x64? Da best!.... If you're a gamer. Otherwise, you better own an animation studio.
If you wanna find out, get some x64 compatible games like FarCry and Half-Life 2. Lahi ra jud.
I'm surprised Adobe Photoshop hasn't gone 64 bit, considering that it is an application that could really use it.
It's the 64 bit version of XP. Majority of applications will run on it, HOWEVER, many DO NOT.
Most antivirus already run on x64, majority of antispyware, not yet.