I now have three UAD cards and have really enjoyed working with the compressors (1176LN, Fairchild and LA2A) and EQ's (Neve, Pultec).
The downside is that the DSP cards aren't particularly powerful and like a lot of other users, one card isn't enough for my needs. I can get by with two cards and smart use of resources, but FedEx have delivered a third today so I should have more than enough juice. Bloody good sounding plugs despite the lack of DSP power. If you look on the likes of Gearslutz, you can pick up some great deals on used cards that already come with the licensed full versions of the plugs. UAD will transfer ther licenses as well. I just got a $50 voucher from them for a card that I bought 2nd hand....can't complain about that.
I'm also very tempted to shell out for the URS CSP too....
As mentioned on another thread, I've had my issues with Cubase 4, so I've gone back to using Nuendo, but others have the UAD/Cubase 4 setup working. It's probably still worth having a browse around both the cubase and UAD forums first.