Please recommend a £350 base unit for work.

Hi all, wondered if I could please get some recommendtions.
Am looking to buy (not build!) a desktop PC, perhaps a Dell, HP, Lenovo or similar.
It is for the mother-in-law, and I really, really need simple & reliable to be the keywords here, to minimise the ongoing support that I currently provide! LOL.

Anyway, any suggestions welcome that meet (or near) the following specs:
Base unit only (will keep current mouse, keyboard, monitor, speakers).
Windows 7 (pro is fine but not needed).
Energy efficient (ish).
Small (ish).
Quiet.
More oomph than the current P4 1.6 system that it will be replacing (so I imagine a Core2Duo system, although i3 would be great).
£400 max budget, but I get bonus points if cheaper :)

Preferably comes with MS Office (else I will buy home & student, despite how much I keep showing her the benefits of Open Office).

I will install Thunderbird, and then Cloudmark which we already have a subscription for.
Thanks for helping.

The Dell Zino HD is relatively small and has low power consumption:

http://www.dmxdimension.com/dell-uk/...d-deals-codes/

The X2 3250e has a TDP of 22W!

Dell also make some slim desktop models too.

There is the Dell Vostro 230 ST:

http://www.dmxdimension.com/dell-uk/...al-comparison/

There is also the Dell Inspiron 560s:

http://www.dmxdimension.com/dell-uk/...on-560s-deals/

Appreciate that. I've managed to spec a full system, inc. Office 2007 basic, for £350 delivered.
Will use that as a baseline to compare against a few others, but it may be the best value.
Cheers

Don't forget an AMD based system though. Many of the Athlon II X3 and X4 processors are at price points which are only matched by slower Intel processors and the AMD motherboards also tend to be a bit cheaper.