Need help overclocking E6600

I'm a bit new to overclocking and I am having difficulty overclocking my E6600 core 2 duo.

I have 1gb kingston ddr2 533 ram, p5vd 2-x asus motherboard, evga 7900gs pcie 16x video card. I have stock cooling with a "coolermaster" case (newegg.com/Product/Product.aspx?Item=N82E16811119129)
and a pretty decent PSU (newegg.com/Product/Product.aspx?Item=N82E16817159055)

Before my ram was at auto 4-4-4-12 and i changed to to 533 5-5-5-15. Cpu was at 266mhz and I can't get anything over 283mhz. Windows wont boot, I get the POST error message. I want to get it up to at least 300mhz.

I have a suspecion that my motherboard may be the problem, its not exactly high end. Also I looked at the guide in the sticky and I'm not sure about the voltage part. I went to the power section under my BIOS and I can't change the voltage (I assume it's automatic?) I can only change it to "ignore.

I have been running my computer on the settings listed above (283mhz, 533 5-5-5-15) and I let orthos run for an hour and a half and everything seemed okay (max temp while running orthos was 55C but it was average of ~45C the whole time) so I figured it was safe to stop testing and play some games. I was playing Warcraft 3 for a while (not exactly cpu intensive) and my computer crashed. Froze while hearing a constant single beep. I must be doing something wrong, help please? Sorry If I wasn't specific.

I dont think you will get very far with that motherboard. Its just not made for overclocking really, and the VIA chipset doesnt help.

You can have a read of the guide in my sig and see if there is anything you can pick up from it :)