You can google the result without tweaks by searching a phenomII x2-550 or 555
You can also get the price of a x2-550 on ebay its less than ~50€
About 32bit vs 64bit in my tests 32bit is faster than 64bit in 7zip.
Native tested in 64bit result is:12800
I need to buy 1 more ram dimm to get the full 128bit ram interface then the result is better.