whats a good stability test to run to make sure my sytem is stable.

I usually use prime95, but there may be better options.

Prime 95 would be the second test that I would do... the first test would be super pi found at xtremesystems.org this test should be the quickest and tell you if it's even somewhat stable... prime would be for long term stable but watch the heat with prime... you dont want to fry your cpu.