CPU Compatability

Well I'm thinking of getting a new CPU and am currently running a AM2 system, with a 4800+ X2 at 2.5GHz and 1Mb of cache.

My budget stands at £100 and I was looking at the new Athlon X2 7750 BE with it's 3.5Mb of cache, now before you start crying intel I don't want to be buying a new motherboard, now my motherboard is a Gigabyte GA-M61P-S3, and lists the following phenom cpu's as compatible:

Phenom X4 9650
Phenom X4 9600
Phenom X4 9550
Phenom X4 9500
Phenom X4 9100e
Phenom X3 8650
Phenom X3 8600
Phenom X3 8400

Now I know if I plug a phenom into my AM2 board the HT speed will be reduced to 1Ghz as opposed to 1.8Ghz - 2.3Ghz, but what I want to know is will a X2 7750 be compatible, as I think it's a case of them not updating the list (They haven't for a while, and the X3's took about a month or so to be added), and if not how do the lower X3's compare to the X2 7750?

Thanks in advance for the help.

Merry Christmas,
mc6415

EDIT: Another quick question is there much of a performance hit with an AM2+ CPU in an AM2 board? eg/ X2 7750 BE or an X3 8650 in an AM2 socket or an X2 6000+ which would give me the best performance for buck?