Depending on your Operating System there are some registry changes you can try. For example, the TCP/IP stack on earlier versions of Windows is not optimised for best performance over a dial-up and you can tweak that. Post the details of your OS and we can advise. Remeber however that no matter how optimised your PC is, if your ISP is providing a terrible service or the internet itself is slow from your location then everything is still going to crawl.
Regarding the '24 Hour Client', I think what you mean is an automatic disconnect after a certain time period. This is forced by the ISP to economise on their use of modems. If it is a timed disconnection, you can often set up the connection properties of your browser or email program to redial and reconnect automatically. If the disconnect comes after a period of inactivity then try setting up a scheduled ping to somewhere on the internet to keep your line up