the whole benefit of online as opposed to live is that you get more hands per hour and being able to 8 table or 4 table or 6 or whatever suits your needs gives you that edge. playing poker is boring, but if you can get 300 or 400 hands an hour as opposed to 60 or 70 live, think of how much more of an advantage you have.
you need equipment to do it right though. you definitely need a flat screen monitor and you MUST have a graphics card and one or more monitors capable of displaying 1600 x 1200 resolution. that way there is no over-lap. all 4 tables fit neatly into one screen so there is no clicking back and forth. i have two monitors next to each other so i can technically 8 table with no overlap, but the most i normally do is 4 and sometimes 6. but i like to use one for poker and one for email and browsing sites like this talking to deadbeats and apparently causing controversy.
might i suggest the dell2001fp flate screen. the best monitor out there by far for poker. you can get em from dell for 600 or so normal times, but lots of times you can get coupons if you search online. i spent 900 shipped for both of mine.
gl