I guess it depends on what you want to do. If you have some good mics, that is a big step in the chain. Next as far as importance would be the preamps, IMO. The preamps on the 2480 while supposedly better than former units in the VS line, are really not that good. They tend to be rather noisy after about 3/4 up.
Some good channels of preamp would be helpful. Keep in mind, with the 2480, you don't have any inserts, so there is no way to bypass the internal preamps. The only work around for this is to use external convertors. So a good set of convertors would help with an external signal chain for critical stuff. And, also as a direct in for your bass and other instruments.
You have dynamics on every channel with the 2480, and they're decent. There's a very cool graphics for the dynamics on the VGA. A good external compressor for your external chain wouldn't be a bad idea either. The RNC gets high marks for being very transparant and very inexpensive, ($200) a much better compressor than units many many times it's price.
Effects on the 2480 are nice. External boxes are a matter of preference.
The EQ is so horrible that it is not really useful. Beyond bad.
If you haven't spent your money yet. I HIGHLY recommend that you look at
an Akai DPS24. A similarly equipped 2480 is very close in price. (Price a 2480 with the burner and extra efx card)
The machines are not in the same league, not even close. If you want more info on this let me know, and I will give you my opinions. I owned the 2480, and sold it for a DPS24.
Taylor
Oh, and stay away from the Roland monitors from what I've heard.