As far as the 2650, and Dell PowerEdge is going to be a good one. As soon as it arrives, I would take it to a local computer shop and have them give it the once over. No sense hooking it up and finding out the motherboard or the onboard video is shot. Or the processor is no good. Personally, I would lease the entire network from Dell.
I would be careful about your desktops. You can a good Lenovo or Dell with 3GB of RAM, the server needs at least 4 (if 32-bit and more if you have 64-bit). If you purchase new, you will have a warranty. The same goes for the server. It's nice to have same day or next day service with a leased or new Dell.
There is also the Microsoft Foundation route, which is basically free.
As to your staff doing things different ways, that is inefficient and unacceptable. Come up with YOUR way, write it down, and THEN have a meeting and get everyone's input. But, everyone needs to be on the same page.
And, make sure if you purchase desktops, DON'T get any home versions.
