The motherboard code means nothing to me - who's the manufacturer? Is it socket AM2 or AM2+?
If your motherboard is AM2+ then you should be able to drop in a new Phenom II and you're flying without having to change anything else. If it's only AM2 then you're probably out of luck and will need new motherboard as well.
In fact, if you're getting a new motherboard then you might as well get socket AM3 so you're up-to-date but you'll have to replace your RAM with DDR3 too.
So, in a nutshell, if your current motherboard is only socket AM2 then you're realistically looking at a whole new system to do an upgrade.