Hmm. Don't know what all your options would be in the UK.
I use an ADSL connection, about 40 - 50 times faster than a56 k modem. If you've never had one, you don't know what you are missing. Costs about 40-50 US dollars per month with free equipment(special modem).
A CABLE connection would be my second choice, because the speeds reportedly slow down during prime time when everyone is watching tv, but a Cable connection is still FAR faster than a 56 k modem.
Failing that, I would want the latest 56 k external modem made by US Robotics (or whoever bought them out). But the little extra bit of performance you might get may not warrant you going out an buying one to replace what you've got. Aces High will run fine on your current modem since it doesn't require a lot of bandwidth.
G'luck
PS - the tweak may seem daunting, but it is actually easy. Just follow it step by step.