Dial-up internet problem

Could someone kindly help me out please?  I received my new XPS 400 (Pentium D, XP Media Center Edition, Intel 537EP modem) on March 06.  My ISP is AT&T.  I have used AT&T for years.  I have loaded the software from the AT&T CD (was totally unable to download it) at least 5 times always removing previous versions each time.  Everytime I have had different problems when accessing the net.  Although it's always slow to connect and to disconnect usually the home page never comes up at all. I have had  ongoing forum messages with AT&T for 3 weeks plus hours and hours searching FAQ's and forums.  I simply can not get the software to work properly.  My old computer has no problems, and never has, with the AT&T software (Micron 'puter, 5 years old, Millenium Edition, Pentium III, USRobotics PCI modem).  That's what I am on right now.  I seriously do not know what the problem is and I have tried every suggestion that AT&T has come up with.

 

In addition, the Dell should be quite fast, online or off, but has never seemed to be even compared to my older computer. When I have connected to the net with the Dell it never got above 48,000kbps.  And that also is slow compared to the same kbps with the old 'puter.  (Same phone cord, same jack.  I just switch the cord between one computer and the other).

 

Any ideas or suggestions?  Thanks to everyone!