AOL has always sucked, i know BT uncapped is expensive, but because they own the line and hardware they problem solve quicker than most ISP's. And i also download about 200 gig's of movie's etc evey month, and to do that you need an unthrottled and uncapped service. AOL has neither, even if they claim otherwise.
Hmnn... now that i think about it, BT does throttle SOME p2p services, but you can work round it with proxys and random ports.
No, has to be run as seperate entities for regulatory reasons.
Also, last persion I know who downloaded that much on BT consumer ISP ended up with a £100 bill....
Beg to differ mate, BT have engineers in all citys and most towns, so they DO respond to problems faster than say Pipex or tiscali 
As for the bandwidth question? well i pay 50 quid a month for an uncapped service, UNCAPPED, so i don't know what you mean by 'consumer ISP' , for me? well it was nearer 250gig's last month (I wanted to catch up on 'Lost') I suppose it depends on what you use you're connection for.
Sorry, you are incorrect. BT do not have mobile ISP engineers. The engineers you see are Openreach engineers, and are entirely unrelated with the ISPs (BT Yahoo, BT Broadband, BT Connect, Plusnet) that BT own. If a BT ISP customer has a line fault, BT ISPs have to use the same BT Wholesale systems and processes as every other BT Wholesale customer, and get the same treatment.
I'm interested in what ISP you use - is it consumer or a business account (Business generally are uncapped). Still, 250Gb is excessive even for a small business. What the hell do you use that much bandwidth for - you'd be better off with a LES10 or similar circuit if your legitimate needs are that high
- That is higher than a 1Mb max'd out line 24/7
My ISP is BT , i get a true 970kb/s download speed, which gives me 60megs/minute and about 3.6 gigs/hr, which at full speed would be about 86 gigs/day.
Now, sky anytime on PC takes up a LITTLE bit of my width, but most is taken up with usenet binaries. All un-copyrighted of course.
So, a 1meg maxed out line as you mentioned, would give a true download speed of about 85-90 kb/s, i have much more. 
As you are a BT customer, you won't have more than an 8Mbit line. Therefore I'm guessing you mean you get 900kb (b=bits), so around 10MB (bytes) per min. 600MB per hour.
What the hell do you download? There is a limit to the number of 'Linux distros' you can download in a month 
Dude, i can download a 4.5 gigabyte DVD in just over an hour, so i have no idea where you get this 600mb thing from. And yes i do have a 8meg line.
Assuming its a copyright free DVD, and assuming you live in a telephone exchange, your best throughput will be a shade over 7000kb/s (bits). So line throughput, shade under 700kB/s (bytes). Add in the IP, TCP, and NNTP protocol overheads, I'd say (without a calculator to work it out), somewhere in the region of 500 - 600kB/s (NNTP isn't hugely efficient, being designed for text). So I'd guess just under 2GB per hour theoretical maximum.
That is assuming 100% throughput capability in the rest of the system - Centrals (likely to be fairly heavily contended), exchange backhaul (likely to be medium/heavy contented), ISP infrastructure (light/medium contention), and assuming you're using a commercial nntp server, transit (medium contention).
The 600MB came from you say 900kb/s - which cannot be 900kB/s from 8Mb line, so assumed you were getting around around 1Mb throughput.