i have a dell vostro 260 with an i3 and want to upgrade, what motherboard/ processor/ SSD can I buy without spending a fortune?

I have already installed a G-force GT640 and added 2 x 4 Gb CORSAIR Vengeance RAM's.

Any advice is gratefully received.What do you want to GAIN from the upgrade?  By which I mean, what do you do with the PC?
Additionally, what's your budget?I use it for gaming, most of the time it 'copes' but i'm wanting my machine not to struggle as sometimes I have to drop out of a GAME at a crucial point because my pc freezes or causes a ping so high I have to rage quit which is really frustrating!

My budget would be as little as possible (having 3 lovely drains on the resources (the kids)) so i'm not looking for the top of the range, just something I can put in that will mean that for example I can turn the graphics up to high in GAMES like PS2 and still have a descent enough FPS.

I heard it can be tricky upgrading a Dell so any advice would be great!

Any ideas?

ThanksA faster CPU may help a little, but your GT 640 will be holding you back in most games.  A decent graphics card will however require you to upgrade the PSU, and potentially the case as it doesn't look like it has all that much airflow so a faster card may run quite hot.
Newer Dells mostly tend to be standards compliant unless they're the really tiny ones, so I can't see anything stopping you from upgrading most parts.
An SSD will help your system feel much, much faster in terms of booting up, shutting down and loading programs and files, but won't help game performance.  I'd recommend the Samsung 840 Pro, Crucial M4, or Plextor M5 series drives.