P4 3.0 dont support window 8 if i remember and i currently have Windows 8 on a pentium D 3.0 2core with 1gb ddr2 and an ati rage pro 1998 8mb for gpu and it work well.. with your 3 gb your ok to run it..
My main have 4gb and i run ubuntu 12.04 Windows 8 virtual without problem..
Goodluck 