Does anyone have a favorite brand of compact flash card? Does the 50D take Type I or Type II cards? What sort of speeds are needed?
Thanks.

Type II is long dead. Check the RG database for write speeds.

http://www.robgalbraith.com/bins/camera_multi_page.asp?cid=6007-9672

EBH

I own the 40D & use the Sandisk Extreme III 2GB CF card that has 30 bytes of read/write speed. Was told that a 4GB card is wasting if you're only a frequent shooter. The advice came from Pro that i have made friends with just recently.

The Canon 50D takes both on the CF card 1 or 2

I can't imagine any ancient Type II card that one would want to use in a 50D. Most of them were microdrives. 50D files are rather large (20MB) and the camera has a high throughput, so an 8GB card is a good match.

EBH

A handful of Sandisk Extreme III's should do the job. Size will depend on how much you shoot but with 15 MP RAW's I'd go for 8 GB cards.