Installed Physical Memory/Total Physical Memory

I assembled a new computer and installed Windows Vista Home SP1 64bit os. System is working fine, no problem, but I have a small query. On this computer I’ve installed 8GB RAM that is showing up properly in BIOS. But when I check the same in Vista System Information, thought it says 8GB RAM, but it is divided into 3.75 gigs total physical memory, and 6.57 available physical memory.

I’m just confused between these Total and Available Physical memories. What is the difference between them?

Did you enable the memory remap feature in BIOS? This will enable
Vista 64 to access all your 8 GB, although only software written to
access more than 2 GB will be able to use it.

Read this. http://support.microsoft.com/kb/950233/en-us

then go to the link on the page that says "View and request hotfix downloads".
Its closer to the top and on the left.

DL the hotfix and Mission Accomplished.