There is not a better CPU than the Phenom 720BE for the 'bang' for your Bulgarian Lev. It will service your needs today and in the foreseeable future with the Radeon HD5850.
If you do not plan to CF take a look at the Gigabyte MA770T-UD3P
If the idea of a future CF is in your plans check out the AM3 790x chipsets.
If you want the rig to survive 3-4 years invest in a good PSU. And in 2 or three years you will be sitting pretty to upgrade the CPU for a much more powerful system.