Performance info for Client/server

We have an existing Database written for Oracle 7 and Forms 3 which we run on a UNIX machine with access via VT220 emulators. We are in the process of converting to Developer 2000 and using it in client/server mode. I have a number of queries about the possible pereformance issues and wondered if anyone had had experience of doing this.

1. How much of a PC do I need for 4.5 to run OK
2. What is the difference in performance between direct connect (VT220) and client server. Should we expect it to be better or worse.
3. Is there any FAQ or similar relating to performance/sizing algorithms for estimating which target machines (s) will provide a comfortable performance.
4. Any one had adverse experience in doing this sort of thing

Thanks in Advance.

-- 
Tony Brown
Arete Software
email: tb_at_arete.demon.co.uk
tel: (01344) 867706
fax: (01344) 867714