As said before, get sdsl. Thats what I used for freehosting for awhile. Always worked, but more expensive, I thnk 1.5 runs about 300-450 a month. I dont think you could afford 1.5gbs, as most people cant, nor will you need that much. I think you might of ment 1.5mbps. At any rate, see how easy it is to upgrade from 768sdsl(thats a nice number to start at), then you can change to 1.5mbps if needed.
Although 1.5mbps sounds nice it won't do... That's downstream speed.
Webhosting utilizes upstream bandwidth, hence the reason why you would need SDSL, (1.5 mbps up and down.)
Ask your telco what the upstream speed of that pipe is. (It most likely will be much less than 1.5mbps...)
IMO, I wouldn't host off dsl. That's just me. I'd prefer to colo my servers in a reputable data center.
Another thing to take into consideration: Although you're hosting relatively small business sites, I'm sure you're customers would still like at least some redaundancy, such as: multiple connections (bgp4), ups, redaundant power supplies etc... (All of which you would get when you colo a server in a data center...)