Best to use the Chroma-Key, select the colors to remove (this negates the need for a totally omni-colored background) and play around with the sliders to give your subject a non-pixelated edge.
As said above- it's an art-form, but good fun nonetheless.
This is all true...best keyer I have used is in After Effects, Keylight...not sure if it's available in an edit package but if you can get it into After Effects, it's quite a step up from the keyer's in FCE...
How does After Effects keyer compare to Shakes?
With that said, can you find the filter you need to use? I don't have Final Cut Express, so I can't tell you exactly what to use, but in Final Cut Pro you have the filters under "Key" labeld chroma key, blue/green screen. Does Final Cut Express have anything like that?
Note very close. Shake has the advantage of having both Keylight and Primatte (along with a luminance keyer) that can be used together to achieve excellent keys. Shake's node-based structure allows you to take the best parts of differeny keyers.
P-Worm
How does After Effects keyer compare to Shakes?