Yup 56K is bad news i'm afraid. I just about live on 64K ISDN but 128K ISDN makes a real difference. Would get cable or broadband but simply cannot buy it where I live.....
Using GameSpy also results in your connection using it's bandwidth for that AFAIK. Make sure any other progs like messenger, ICQ or whatever are also shutdown.
If you can find a server that you can connect to directly (some mates perhaps) you could see if that is better. i.e. a direct connection. I am going to do some testing on this with my pals soon, some of which have 56K access (hence the test) so i'll let u know.
I don't know where else ppl on here go other than GameSpy. I am new here. I am sure they will reply and let us know
Cheers,
Steel