First time overclock, X700

I know what you're thinking, "X700?!?!..ewww" Indeed. I was planning to dump an x1950 into this rig to atleast last me a little while since I began to play Source...but I realized my PSU probably could not handle it. Last thing I want is to have to buy a new power supply as well just to last me till the end of the year for x38/penryn/G90/R700.

I was a bit bummed thinking my ATI x700 didn't contain the temperature monitoring feature. But after installing ATI Tools to my astonishment it does.

Now here are my questions. I've overclocked my CPU before from 3.2 to 4 ghz (prescott) with a stable overclock. Tested that sucker like crazy. But for GFX cards I'm a complete newbie. I've been reading up on some guides and got a basis on what I have to do but what software would best test the overclock to look for artifacts? Ati tool has a built in artifact checker but is it any good? I was planning to install 3d mark 2003 or something similar and just watch for artifacts. That's what this guide said to do but it is a bit outdated so curious on what you all think.

Right now the GPU temperature is idling at 42C while the memory is at 37C. After running that ATI tool artifact checkers for several minutes, the gpu tops of at 63C while the memory shows 40c. Could anyone mention the temperature thresholds that I shouuld try to avoid? The guides I have read have said nothing about the temperatures so I was a bit worried. Last thing I want is this x700 to fry and lose the only graphics card I have that has to last me till the end of the year. I currently have one of those PCI slot dual fans sitting below my graphics card for extra cooling. So hopefully that hsould help with temps. Is it also worth removing the original thermal diode and replace it with AS5? I have some laying around here somewhere that was last used about 3-4 months ago. Also, Should I go about disabling the temperature controlled fan and just set it to 100%?..or should I just let it be?...bah the choices.

Looking forward to your responses. Hopefully I can get some extra frame rates out of this sucker till my new rig at the end of the year. Kinda tired of getting such low frame rates in source >_<.

-Update
I've been tweaking with the clock speeds so far and got it up to 486 core and 502.20 memory clocks. Up from the default 425 core and 432 memory. The core is above the x700 xt which is rated at 475...The memory clock is at .30 less then the x700 xt....Having a feissues I'm worried about. Like the computer completely becoming unresponsive with a crazy chaotic screen. The craziness ensued around a 495 core and 506 memory clock. I bumped it down and so far running it fine. The weird thing is I wasn't getting any artifacts and yet the screen went crazy and the system became unresponsive. Not very cool at all =(....But running ati tool then going to run a number of passes through 3dmark 03/05/06. god I need a new computer...lol...but hopefully this clock should give me a little extra needed performance till I get my new rig. I'm probably gonna re-oc my 3.2 prescott back up to 4 ghz or slightly higher again. Really need some performance atm.