Western Digital Diagnostic Tool

I’ve found what might be a good tool for checking your Western Digital SATA drives.
It’s called “Data Lifeguard Diagnostic”
You can download it from here http://support.wdc.com/product/download.asp?groupid=606&sid=3&lang=en
But you might want to check this page, http://support.wdc.com/product/download.asp?level1=6&lang=en first to find your model of disk and make sure it is compatible with the tool

Memory Limits for Windows

Physical Memory Limits: Windows 7

The following table specifies the limits on physical memory for Windows 7.

Version Limit on X86 Limit on X64
Windows 7 Ultimate 4 GB 192 GB
Windows 7 Enterprise 4 GB 192 GB
Windows 7 Professional 4 GB 192 GB
Windows 7 Home Premium 4 GB 16 GB
Windows 7 Home Basic 4 GB 8 GB
Windows 7 Starter 2 GB N/A

for information on other versions of Windows see here : Memory Limits for Windows Releases