There are two variations of all the different Windows 7 versions available, a 32 bit version and a 64 bit version. If you want to try the 64 bit version you will need a 64 bit processor from either Intel or AMD and you need to make sure that your PC meets the minimun requirements.

The published minimum system requirements for Windows 7 64 bit are:

• 1 gigahertz (GHz) 64-bit (x86) processor
• 2 GB RAM (64-bit)
• 20 GB available hard disk space
• DirectX 9 graphics device with WDDM 1.0 or higher driver

By using 64 bits you open up a whole new world of possibilities, specifically in the realm of lots of system memory. With 32-bit Windows 7, you’re stuck at 4GB of RAM and probably due to some boring technical stuff about memory mapping, only about 3.3GB is available. With 64-bit, 4GB is just the start. You can run loads of applications simultaneously without the system slowing down for swapping. Windows 7 runs nicely in 4GB of RAM and 8GB (and more) becomes a reality (although you need to check how much your motherboard supports).

So what processor do I need to run Windows 7 64 bits?

Intel
In a nutshell you need an Intel Core 2 Duo, an Intel Core i7 or and Intel Core i5 processor.

There are some other Intel processors which supported 64 bits before the Intel Core 2 Duo including:

• Some Xeon models
  
• Pentium D
  
• Pentium Extreme Edition
  
• Pentium Dual Core (E2140, E2160, E2180, E2200, E2220, E5200, E5300,
• E5400, E6300, E6500, T2310, T2330, T2370, T2390, and T3200)
  
• Celeron (Celeron 4×0; Celeron M 5xx)
  

AMD
If you have an AMD processor it is normally a bit easier to tell if it supprts 64 bits as it will have the number 64 in the processor title. So all Athlon 64, Athlon 64 X2, Athlon 64 FX processors support 64 bits (clever huh?). But also the following AMD processors are 64 bit compatible:

• Athlon II
  
• Opteron
  
• Phenom
  
• Phenom II
  

For more information you might like the following pages in Wikipedia: x86-64 and 64-bit.