Possible to see to biggest difference in graphics applications such as Adobe Photoshop at 64-bit transition.
Also Cyberlink PowerDVD benefits from 64-bit transition. Before buying this kind of 64-bit versions of applications you have to learn whether the license is 32 bits or 64 bits and you have to learn whether you are eligible to free transition to 64Bit
The biggest difference this new generation of applications using the DirectX 11 GPU with up to 10 times instead of the CPU is to provide higher performance. This trend will continue to become more widespread in the future.
Windows 7 64-bit, DirectX 11 and next-generation processors, graphics cards, faster DDR3 memory, SSDs and more ... If you use a combination of all bombs expensive but will give a great performance for sure.
To summarize, a new and powerful 64-bit computer now should be your choice. After this moment, you should choose 32 bits, there's no reason other than necessities.