Need some "opinions" and "what do you thinks"!

[The Qban]

I am building a server for my company, i wanted to get a HP ProLiant, but just not worth the cost knowing that i can get more of what i want for less. So i have decided to build my own. I have done some searching and sought out what i would think is a credible server.
I have maybe 80 - 90 endusers, so processing power is a must. I run a Taxi Cabs Central dispatching office. We currently have a workstation that a previous IT used to load server. Not very smart if you ask me. There are about 75 cabs on the streets now and they all have cellphones that have an ip and a java software that is used to communicate back with the server. Whether it be gps, runs to pick up, fares, charges, etc. Then i have 7 computers on the network in the office that the dispatchers use to type in al the fares that people call in to get picked up at. It basically takes away human interaction with the drivers trying to assign fares. This software does it faster and more efficiently using GPS and the internet (IP).
I have always worked with networks and servers and computers. But i have only built desktops and laptops before and have always just loaded a preconfigured server, never built a server from scratch. So we'll see how it goes.
Here is what i have, tell me what you all think about the build

--ASUS Z7S WS Dual LGA 771 Intel 5400 FSB 1600/1333/1066Mhz

--Intel Zeon X5450 Harpertown 3.0 Ghz Quad-Core Model BX80574X5450A
12Mb L2 Cache 45NM

-- Kingston 8gb(4x2) 240 DDR2 800 PC 6400 FB-DIMM

--Raid Card 3Ware 9650SE-4LPML SATAII Controller 256MB DDR2 533 Raid 0,1,5,10 64 Bit Support

And i am putting server standard 2003 R2 64 Bit SP2

 

[just a noob]

have you considered going the xeon i7 way? you would have 16 threads available, otherwise the current build does look decent

 

[The Qban]

Well i was thinking about the I7, but then this server that i am looking at building is already gonna be about 5500. I dont think i can afford the price for what 8 gigs of DDR3 memory and and DDR3 capable motherboard would cost. I only have 1 application taht runs on the server anyway, i dont have anything else running but that one application, so i am raelly only worried about getting all the processing power to that one aplication, not really worried about running anything else. I let my ISP provide me with DHCP for the workstations and DNS for the network.

 

[just a noob]

so long as its the one application, you should do fine, but i would just check how much more the i7 build would cost you, and what country are you in(U.S. i'm guessing?)