Make sure you get Windows Server 64bit edition so you can utilize the 8gb of memory.
Yes, this sounds like a great start! We just split our database server to a new physical machine which has dual quad cores and 12GB of ram. SQL is a processor monster so make sure you have as much processing power as you can afford for the database server. Our dual core processor was just not cutting it for all the SQL searches, in fact the entire system would lock up and wait for each search to complete before going to the next search; the processor was working at 100%, 90% of the time. With the dual quad cores the processor never gets over 30% now!! Of course that all depends how many users you have performing searches at the same time.
This is what I found with the dual core; one search would jump the processor utilization to 50%, two searches would jump to 100% and the third search would have to wait until the others were complete. You get the idea of the snowball effect.
FYI - Our 1TB archive server lasted 2 years before getting full with 114 CAD users.