Peachtree Complete Accounting 2008 - Limitations and Slow Down of computer processing.

We have just installed the Peachtree Complete Accounting 2008 program. We are trying to run the old Peachtree 2000 and the new one during March as a comparison.  Asking their technical support these questions is not getting the answers we need.  When entering our "beginning balance" entries there were no warning messages or limitations to the number of invoices that were entered, BUT when trying to access the information later, only the first 200 were accessible. You could see them on the 'list', but they were grayed out.  Payments can be applied to all of them, but the sort order only accesses the first 200 invoices. When calling technical support to complain that NOWHERE in their documentation does it state there were limitations, they had to look it up and said, "yes you are correct, it is not in there"  AND they were not even aware of this. Ours is a service company.  We print on average approx 1,000 checks a month to our vendors and invoice about 500-600 services each week.  We do not need the parts of their program that offer inventory tracking, payroll etc.

Five users have access to the data which is stored on the server - Microsoft Small Business Server 2003..

Also, the application runs slow on the individual work stations even with all other applications closed. The workstations are Dell Dimension 2400 computers, running XP Pro, SP2,  with a 40 g hard drive and 1 g RAM - A suggestion was made to have a seperate server for this application, but we cannot see why that would be necessary. The old program ran fine without interferring at all with speed on any computers.

This being said, our questions are:
Does anyone know of a way to customize the program to get around or remove the limitations?
Is it possible to move or make dormant the components we do not need so the application does not even touch on those components? (We do not want to delete them, for obvious reasons)
A solution to the slow down of processing?