You are very optimistic. PR is lousy at chroma keying. There are three alternatives:
1. ULTRA, very easy to use, short learning cuve, very good results, stand alone, part of the Production Studio
2. KEYLIGHT in AE, steep learning curve, excellent results, can de used with dynamic link in CS4
3. PRIMATTE, a separate plug-in with a very good press.
Kugar, as Harm says, PP keying is mediocre at best. If your lighting is perfect and you've gone to great lengths to avoid fringing on your subject then maybe the PP key would be OK. I recently did some in-PP keying and it was OK, but then my output medium was a small web-delivered flash file.
I'm a big fan of Primatte, but there is a learning curve. Don't even think of attempting it without their companion PDF that comes with the software. And the render times.... yaaaaawwwnnnnn. But for less-than-perfect source footage, it does come up with the goods.
Harm, I was under the impression that Ultra had been dropped from CS4?? Can you still purchase it from somewhere??
*edit* The Adobe website says you can purchase the software Stand Alone, but I couldn't find it in the Adobe store??
If you had Ultra CS3 as part of the Production Studio, you have to install one of the key components of the CS3 Studio (I chose Flash, because of it's small footprint) and can then install Ultra CS3. If you leave out one of these key components, Ultra will install as a trial version and stop working after 30 days.
Thanks guys! I seriously appreciate the help. I'm using the CS2 suite (yeah, ancient), so I don't think Ultra came with it. I'll be checking out the programs you suggested. I tend to shy away from non Adobe products, so I'll prob try to go for a copy of Ultra. Is it silly for me to worry about compatibility issues with non-adobe software?