Question about performance

Got a quick question for the must experienced peeps out there and the number
crunchers.

One of our custumers is currently running SBS 2003 and a 2000 Server
(Terminal Services and File Server)
They have 25 users, 5 of those are Terminal Services.

All the users are running Office apps, Outlook (Setup to use Exchange) and
3-4 third party apps (3rd party as none-MS apps). Those apps are office
tools, nothing fancy (Like graphic or video editing or anything like that).
Right now the whole system is working like a charm.

Anyways, they're going to be changing their main application, and it is
going to need SQL Server. They're also going to be adding more users, and
moving everybody to Terminal Services. Basically this is how it's going to
look

*-*-*-*-*-*-*-*
- 40 users, all running over TS. They're going to be running Office, Outlook
and 3-4 other "office apps"
- Another 100-ish users are going to have access to a SQL database thru a
website. They have a T1, so the plan is to host the website locally since
the app they're changing to is going to generate properties information and
make it available to their costumers.
- The website they are going to be hosting is expected to get around 1000+
hits a day (Low traffic site, but all of it related to SQL)
- There are talks about installing the Blackberry SBS Server since some
users are using Blackberry already (Uppermanagement only, around 10 users)

Now, we're going to be upgrading the server hardware. The initial drawing I
had in mind looks like this:

Server 1 - SBS Server (Domain Controller, Terminal Server Licensing Server,
Exchange Server, OWA, OMA**)
* Single CPU, 1GB Memory, RAID0, USB HD Backup Daily. Downtime of up
to 6 hours is ok in case of failure.

Server 2 - Windows 2003 (VPN Server, Terminal Services Server, File Server,
Blackberry SBS Server**, Web Server)
* Dual XEON CPU, 4+ GB Memory, RAID0, USB HD Backup Daily. Downtime
of up to 2 hours is ok in case of failure.

Server 3 - Windows 2004 (SQL Server)
* Single CPU, 1GB Memory, Raid0, USB HD Backup Dialy. Downtime of up
to 2 hours is ok in case of failure.

** Haven't decided yet between Blackberry and OMA, since they're using and
liking Blackberry that's probably the way to go.
*-*-*-*-*-*-*-*-

The question is:

Would it be OK to combine Server 2 and 3 into a single server? The way I see
it, if server 2 or 3 goes down, their whole system does anyways. So why not
have them all running on a single machine? Is the performance going to be a
problem?

If we go with 2 server, the layout is going to look like this:

Server 1 - SBS Server (Domain Controller, Terminal Server Licensing Server,
Exchange Server, OWA, OMA**)
* Single CPU, 1GB Memory, RAID0, USB HD Backup Daily. Downtime of up
to 6 hours is ok in case of failure.

Server 2 - Windows 2003 Server (VPN Server, Terminal Services Server, File
Server, Blackberry Server**, Web Server, SQL Server)
* Dual XEON CPU, up to 16 GB Memory, Raid5 (3 x 200 GB Hard
Drives), HotSwap SATA Daily Backup. Downtime of up to 2 hours is ok in case
of failure.

Let me finish by saying that money here is NOT a problem (Nice to have one
of those clients once in a while, isn't?). I'm kind of thinking about 2
server from an administrative/repair point of view... But the must important
thing above all is PERFORMANCE.

Anyway, any help or tips is more then welcome

LMC