Dude, I don't know too much about computers, but I've been researching GeForce 4 Ti 4200 64mb cards for about 2 weeks now. Extensively.
Yes, Asus and MSI are good cards for oc'ing. You can "86" Asus right away because you won't find them for cheaper than $170 or so. Unless of course you don't mind paying that much.
From my gatherings, the Leadtek Ti 4200 64mb seems to be the best bang for your buck.(I'm getting one once I get enough cash) It has a tremendous heatsink for stock overclocking. I've also read that they make quality cards and have great customer service.
I've also read alot of good things about Gainward and Chaintech. Plus, these will be the cheapest non-generic cards out there. There are quite a few websites which have Retail Chaintech and Gainward Ti 4200 64mb for right at $127.00 w/Free Shipping.
If you are interested in the Leadtek, go to Newegg.com. They have a Retail Leadtek Ti 4200 64mb for $139.00 w/Free Shipping. Check out the pic of that HSF. Beautiful.
Hope this helps.