Questions
Q1
Why my H61 chipset motherboard will only support 2.49G in system memory in Windows XP when insert a 4G memory module?

Please press Delete key in POST screen to go to CMOS setup.

Then go to Chipset> Low MMIO Align and set to 64MB.

It will help to release some memory space for the Windows XP and system should support to 3.0G memory size.