Partial New Build For ~£250

Hi Guys,

I haven't upgraded my current rig in a few years so it's fallen behind in terms of spec quite a lot, it currently is..

Athlon 64 3000+
1 Gig DDR400
nForce 4 mobo
Geforce 6800 GT
160 Gig HDD

I'm a student so funds are quite tight so ideally I'd like to upgrade the CPU, Mobo, RAM and Graphics card for roughly £250. It obviously isn't going to be amazing but it will always be a huge upgrade compared to what I've got now! I'd like to be able to play modern and new games at medium detail if possible (I've got a 23" Samsung, 1920x1080 display). I've seen Intel had rebranded what were essentially original generation Core 2 Duos as Intel Dual Core which you can get for just over £50, add a mobo for £40, RAM the same and then the graphics card is open to debate. I don't know if this is the best option though and if AMD would have better potential. Here's all I need..

CPU: Quad-core not necessarry - dual cores are obviously cheaper so unless it works out well for a quad core, I don't need it.
RAM: 4 Gigs, ideally better than 'value' RAM.
Mobo: Decently specced, doesn't need amazing overclocking features. On this note though, if I went for an Intel are there big gains to be had from OCing?
Graphics: I'm thinking a last generation mid-high spec card - AMD 4870? They're going for around £100 now.

Thanks for any input!