The 64bit platform in the long run will be more stable and open up some new doors for programming, gaming, etc. there. At the present time it's simply now starting to get noticed since Vista's release. The games, apps, drivers are still primarily for the 32bit verions.
The move upto 64bit from 32 will be seen in the next few years following the next version of Windows when Microsoft plans to halt producing 32bit editions all together. One comparison would be looking going from 95 16bit to 98 32bit where 98 offered more while being looked at as a slower version at the time with people then waiting to see drivers come out like with any new version.
Microsoft hasn't keep up too much with the drastic faster paced changes seen in hardwares. Most running the 64bit releases at this time do so simply to run 4gb of memory and see more then the 3gb barrier common with 32bit. Actual performances vary depending on the system you have.