Upgrade to Microsoft Windows Small Business Server 2008

[xavier1693]

I was going to be upgrading my server to SBS 2008 X64. Do I need to buy any asprin first? Can I even do an upgrade or is this going to be a clean install?
Currently running:
Intel SR1400 Rack Server
Windows 2k3 x86 with 4GB DDR
Dual Intel Xeon 3.0GHz with HT
Dual WDC WD2500SD-01KCC0 (232 GB, SATA no RAID)

Server is running as a Web Server, FTP Server, and a Domain Controler and
it would be OK with me if I can just do an upgrade, but I guess I could get all my server roles going again. I will keep my fingers crossed. Any suggestions before I begin?

[SalVatore]

Here I have little information which helps to make your decision.

1. Customers can buy Windows SBS 2008 with Windows Server 2008 SP2 typical and Premium version software and 5 Client Access License Packs straight from HP or from their HP official dispenser and reseller.
2. Windows SBS 2008 with Windows Server 2008 SP2 is advertised with a HP ProLiant ML/DL100 and ML/DL300 chain servers moreover preinstalled or on DVD.