Agreed. In almost all possible Internet-side server scenarios, the dialup link will be the bottleneck. Exceptions would be if the platform is used for non Internet-service related CPU intensive activities.
For example, if you were hosting a web-site on the platform AND trying to break a mathematically computationally complex algorithm, you could run into problems. Same hold true if you were doing CAD on the same box.
However, if you are hosting Internet-based services and not bogging down the platform/CPU with other activities, then you can be assured that bottleneck will be the 56K dialup.
You can always run the <B>top</B> command to take a quick look.