Getting the right radiator is the most tricky part
I'm not sure about the one at radiator express, but advanced auto and pepboys both have the wrong part number for a 4th gen VTEC. I got mine from radiator.com and was very happy with them.
As far as installing it, its pretty straight forward. Drain, remove bolts, remove hoses, take out radiator, switch fans to the new one, then put everything back together. I would recommend you replace the hoses while you are in there though, as they tend to leak and get brittle as they get older.
Good luck