Cheval_Blanc

you can upgrade to Win7 32 Bits, but you need to avoid the the user interface of Windows Aero

the requirements of Win7 64bits & Win8 are similar, but it maybe a little bit "laggy" if you insist to run on your platform
maybe you can check the following links before making your decision:

Win7: http://zh.wikipedia.org/wiki/Windows_7
Windows Aero: http://zh.wikipedia.org/wiki/Windows_Aero
Win8: http://zh.wikipedia.org/wiki/Windows_8

Cheval_Blanc

This is the specification of your CPU
http://ark.intel.com/products/27 ... _73-GHz-533-MHz-FSB

Clock Speed - 1.73GHz
SSE2  - Instruction Set 32-bit
PAE  - Physical Address Extensions  32-bit
NX  - with Execute Disable Bit

your CPU meet the minimum requirement of W8 in 32-bits, you can give a try
But if you are looking for a satisfied working platform, the CPU need to be upgraded which fulfilled a long-term usage

Cheval_Blanc

Pentimum M Banias  1.50GHz
http://ark.intel.com/products/27 ... M-Cache-400-MHz-FSB
NX - Execute Disable Bit        No

This CPU was old-fashioned and fail to meet the requirement of W7 & W8