If you are looking for a server build, check out this combo from Newegg for just over $900 and it gives you the option to add a second processor later. http://www.newegg.com/Product/ComboBundleDetails.aspx?ItemList=Combo.539649
As for whether it would be better to get this now rather than later, it would probably depend on how long it would be before you would be purchasing it. For video encoding, you are going to want either a i7 920 or higher or a phenom II X6. Integrated graphics would be fine for what you want to do.
For HD video, you will need a blu ray burner.