I've had success with old apps that are unsupported in XP by running them in W98 inside a virtual machine booted on Win2003 Server or WinXP. For an old Win 3.X package you should not notice any difference in performance.
That could work indefinitely, but if you decided after all to switch to a native XP package in the future then virtual machines also simplify this by letting you very easily create and manage test installations to use while you are doing things like configuring your reports, importing data, and so on.
I find VMWare the best, but there is also Virtual PC, which is cheaper and should be sufficient for this task.
