New motherboard

Hello,
im looking to buy a new motherboard for my pc.
its originally an acer aspire x3400

its spec are:
amd athlon II x3 2.7
6gb (3x2gb) ddr3 1066 ram
redeon hd 5570 1gb
1tb hdd
dvd-rw
Win7 home premium

ive got a xclio a380 case for free so im gunna use that,
and im also getting a radeon hd 6870 1gb
and a 750watt psu

I wanna get a new motherboard for 40-60quid
its not much but I aint got loads of money.
I want the motherboard to have core unlocking, and overclocking capabilities
preferably 4 slots for ddr3 ram
and I need to be able to use my current processor with it.

I seen a asrock extreme3 for 60 quid and that looks ok its on ebay
and an asus one on scan.co.uk

any suggestion?

thanks alot