Exactly. I go through about 3.5 gigs a month on WoW lately, WoW itself is not eating up any BW, but being on Ventrilo talking for 6 hours while doing MC/BWL/AQ uses up about 350 megs along with WoW for the night.
2 raids a week and well yeah, its gone pretty quick.
But at the end of the month, I've still usually got 500 megs or so left (if I buy 4 gigs), with any of the other options from other ISP's you would lose that 500 megs. So now basically every 2 months I get 1 Gig back free which I would lose from the other ISP, so you end up saving R125 every two months.
Plus say I buy a gig at the end of the month and I end up having to go away for work for 3 weeks.. so what, I get back and my BW is still there.
I now usually watch my BW and when I get to 200 megs, I log on to their site, buy an extra gig, and I'm set again without any downtime or interuptions