Below are the Windows 7 minimum requirements:
- 1GHz processor (32- or 64-bit)
- 1GB of main memory
- 16GB of available disk space
- Support for DX9 graphics with 128MB of memory (for the Aero interface)
- A DVD-R/W drive
Most of the PCs right now should have the specifications above and by the time Windows 7 launches and they still keep the requirements, the new operating system should do well.