Build Advice £200 upgrade options?

Hi,

I've been asked to upgrade a PC with a budget of about £200 for fairly standard non-gaming use.

Budget: £200 (but I'm not sure if that much is necessary)
Main uses of intended build: word/excel, streaming and media server
Parts required: CPU, mobo and maybe RAM
Previous build information (list details of parts):
M4A78LT-M
Phenom II X2 555 BE
Corsair HX520
2x 2GB 1600Mhz RAM
Storage requirements: n/a - have SSD + HD
Will you be overclocking: no
Any motherboard requirements (no. of USB, Xfire/SLI, fan headers): SATA 6GB/s, simply to get the best out of the SSD.
Extra information about desired system:

I'm torn between which cpu route to go down; FM2, AM1 or Pentium K

For example:
AMD A6-6400K
AMD Athlon 5350, Kabini, Quad Core, AM1, 2.05GHz

Any thoughts on this would be very welcome

Tempted to pick up one of these so that it could sit on a desk as well
Hyperion EV33B Cube MATX Case

Thanks!

 

Was it the x2 555 the one where you can unlock to a quad and then OC?

 

Yes, it was that one but unfortunately of the two I bought, this one didn't.

 

Anyone?

I'm leaning towards the FM2 but it would be good for someone else to agree/disagree.

It's not my money so I'm keen not to get this wrong. Thanks

 

FM 2 is a great choice. Easily within budget and decent performance.