I'm looking for recommendations on what I should be looking for in a
firewall and any recommendations on a specific firewall or brand.

I have setup Sonicwall TZ 170's and ISA 2000 so I'm not illiterate on the
subject but far from any expert.

A problem I've had with ISA in the past was that all outbound traffic came
through a single IP address which caused problems with the email servers.
(I'm not certain this was due to ISA but it appeared to be). Additionally
since it runs on server hardware I'm concerned that routing all the traffic
through an ISA server may cause bottlenecks.

Our environment is this:

We are hosting with a good sized hosting company. (Meaning we are not
hosting ourselves with the local cable company or via the phone company)

We have 5 servers (Email and Web)

We currently have 10 IP addresses

I need to make sure running traffic through the firewall doesn't create a
bottleneck. (We currently average about 500Kbps sometimes spiking to over

I can't have the problem I had with ISA where all outbound traffic went
through a single IP address.

I really only need to route the traffic and block ports.

I don't currently need port mapping, port redirection, or VPN

Thanks for any suggestions!