FEBA,
The stuff following is applicable to UK users.
It depends on what you intend using the BB feed for. If it's going to be surfing/downloading, then the "headline" figure quoted for ADSL is the DOWNLOAD max transfer rate.
The "A" part of ADSL means it's asymmetric which simply translates into you getting a much faster download (into your PC) rate than upload (out of your PC) rate. e.g. most UK ADSL services will have 512kb/s download and 256kb/s upload. I've just gone for a 1Mb/s upgrade and the upload remains at 256kb/s.
What that means to me is that downloading is approximately twice as fast as it was (assuming that the source material is coming from someone with a much better upload figure than mine) and that web pages load in about half the time. Video streaming is less likely to stutter as it plays as well.
The only downside that my kids have noticed when they play on-line games is that the ping (time taken to send a data packet from my PC to a remote PC/server and get a reply) hasn't reduced by very much (we reckon about 10%) and that seems to be because the upload bandwidth is still at 256kb.
The other factor to consider with ADSL is the contention ratio. That is normally 50:1 for domestic services which means that you could be sharing your access to the network at your local BT exchange with up to 49 other people at any given time. In reality it's not as bad as it sounds because unless a lot of those other users are also hogging bandwidth by leaving PCs running with downloads of very large files in progress, statistically its unlikely to have any marked effect on how you percieve the "quickness" of your connection.
You can get symmetric DSL connections but you'll pay a premium for them.
I have no experience of cable connections and therefore can't comment on their symmetry or contention ratios.
The BT website used to have a list of ISPs that use them as the network provider and customer access company, it would be worth looking at
http://www.bt.com/broadband to see if that list is still there and you can then have a trawl through the ISPs listed to see if they provide the sort of service at the price you are willing to pay.
Hope that lot helps.
Cheers
ST