PIX or router

I want o move one of my customers from ISA to a hardware router/firewall.

The site currently has 25 users but might grow to 40 or 50 in the netxt 2 or 3 years. Some of the new ones will be remote users and they are also starting to use a remote facility as well.
Ideally I would get a PIX and a Router but i don’t think I can convince them that’s the way to go.
The PIX should be able to do some routing and the ROUTERS should be able to give me some type of endpoint security.
What suggestions can you give?
Would they be better server with a PIX 501 (506) or a 800 series router?