Most brands will OC to stock Ti500's, but some will OC even farther than that. Here are some of the best, in order from best to not quite the best but still really good. Asus V8200, Leadtek, Gigabyte. If you want to see other brands OC'ing abilities go to the normal Tom's Hardware page, click on key word index, then click the letter g, then somewhere in the top several listings, one should read Win, Lose, or TI, 21 ti boards or something like that. Click that, scroll to the bottom and click Overclocking. Also if you are going to OC your graphics card think about an additional fan mounted right next to it or on it. This can significantly raise its OC potential, and a good fan can be found for around $15, and additional heat sinks shouldnt be too much either.
The first LAN I went to was at a PETA convention. They booted me after I shot a zombie in HL DM!