I have an Oxygen VX1. Great card for cad and 3D. I got it for under $75 and it has paid for itself at least 4 times. My render times were cut in half after I bought it. Get at least a 32 meg card. Now that the Wildcat III is out, the wildcat IIs and original wildacts will be even cheaper. So, if you have the money, go for a wildcat. The problem with 3Dlabs is that there is little to no games support, so if you do any gaming, you will have to run the game in safe mode.
Oxygens are nice though, the best deals are in order: Oxygen GVX1 32, Oxygen VX1 32, Oxygen GVX1 Pro 64, Oxygen GVX420, OxygenGVX210. (I don't even count the old VX1 16 because it is a piece of ***)
The GVX1 is a good deal because it provides very good rendering for its price, but if you are strapped for cash, go with the VX1. The VX1 isn't great, but it is a good "first pro card"
The GVX1 Pro, has a full 64 megs and that amount of memory becomes essential when dealing with polys or splines in the millions.
The GVX420 is 128 megs and produces excellent render times, this is the premier oxygen and is not only the size of a dinner platter, but is absolutely godlike. The 210 is more like a souped up GVX1 pro, the pro is a better deal, and if you have enough money for a 210, you should save up a bit and buy a 420.
That is my take on the Oxygen line, I would look on Ebay if I were you. Ebay is the only place you will find a 420 in mint condition for under $1000...