I have found a RAM error with MemTest86+ (the version included with Ubuntu 13.04), it says:
Failing address: 002f796c48 - 759.5 MB
I have no money to buy new RAM now and the error seems to be single so I hope I can just override it.
In Linux there is a memmap kernel parameter that can be specified in the boot loader configuration file lets to blacklist a particular RAM area easily.
Perhaps there is a similar parameter boot.ini parameter or other way to do the same in Windows? I am interested in both Windows 7 and XP solutions.