Too lazy to quote, but if you think anyone with some money can have DSL or cable internet then you're just ignorant. In my case, the closest cable internet/TV service is available 0.7 miles to the east of me and 1 mile to the west of me (distances quoted from our closest cable provider), but the estate I'm on isnt in range of a cable hookup. If you could see where I live you'd be pretty suprised by this.
An $800 computer doesnt equate to a high-speed connection, unless you're willing to shell out $33,000 to the cable company so they'll reach out your way (yes, they quoted to us that it would cost $33,000 to hook up 1 mile of cable service).
Mechwarrior 4 is very playable on dialup (400 ping) and is probably the closest you'll ever come to a fun FPS experience on 56k. I played it competitively for 2 years on a 56k connection, often while using Teamspeak in a 16-player server (huzzah for 56k!). However it all depends on your connection. AOL, for example, spells DEATH on dial-up. My friend tried Mechwarrior on AOL and had consistent 700-900 pings, but I used AT&T and got by okay. Also, Mechs move kinda slowly so ping isn't has unforgiving as in a game where you're controlling a running human.
Tips: when playing online on 56k turn off everything you don't need running in the background, like AIM/MSN messenger, automatic updates (on any program), etc. Some dial-up providers also provide a free Internet Accelerator program which may or may not help in gaming lag.