An A2000 is a good computer. It's the only computer I've actually owned exept for the A500 I upgraded from, a looong time ago. display options are getting a little slim these days. The spectrum 128 is not bad, it does have a pass thru for std amiga screens but you will have to have a SD/FF, the card will then automaticly switch modes.
A Picasso 4 on the other hand has a built in SD/FF, they are getting to be rare now but they can provide higher resolutions than Spectrum, Max res for me on Spectrum in tru / hi color seems to be 800 X 600. On Pic4 you can go up at least 3 more notches. Now don't expect blazing speed here the 2000 has a sloow bus but you can play DOOM
on a full screen with a decent accelerator. I have both cards on my sys to support 2 monitors. Check profile to see the stuff that is stuffed into this crazy thing.
Good Luck
Chris
PS if you get the A2000 I might be able to supply you with a 030 40Mhz combo accelerator card.