Really, any good LCD is going to be great for video editing. the place where a good monitor really counts is on external preview, whether you choose to go with a DVi input television, or something like that. I use very inexpensive CTX monitors for much of my editing, plus a pair of Mitsubishis in another room. I personally, prefer two 15" or 17" over a single 21". I have all three rigs, and I LOVE my 17" setup, on a parhelia.
Save bucks on the computer monitor and spend the savings towards a great broadcast monitor. (Unless you are only doing vid for the web)
That's my input, anway.
We'll be showing the awesome Sony Luma monitors on the VASST tour leaving out next week.