If you don't game much, then the Intel Core i3 is a good choice. Between the Phenom II and i3, I'm not sure which one is faster at sql server 2010. If you get Core i3, there are some boards out there like ASUS P8B WS or P8C WS that will allow you to use ECC with ONLY Core i3 or Xeon, not the i5 or i7. The Phenom II will have ECC support all over. This maybe important for your sql server activities.
On another note, the i3 only sips about half or less of the power of the Phenom II. The A8 somewhere in between.
Intel comes out on top for Server benches, see:http://www.anandtech.com/show/5553/the-xeon-e52600-dual-sandybridge-for-servers/8
I think the i3 and the Phenom II will be a close race in server benches, but the i3 will sip 1/2 the power.