Upgrading my computer to a GTX 770

[Will Baggott]

I've had my computer for just over a year and I want to upgrade it as the graphics card I have installed at the moment isn't good quality. I have an Advent DT2410 http://www.pcworld.ie/Product/ADVENT-DT2410-Desktop-PC/312213/307 and I want to upgrade it with a GTX 770, which I know I will need to upgrade my PSU for it to be installed. I was wondering two things:

> Whether my computer is upgradable
> Whether the people at OverClockers could upgrade my computer for me (With me buying the parts from them)

The PSU I'll be getting is the http://www.overclockers.co.uk/showproduct.php?prodid=CA-070-AK

 

[Will Baggott]

Do you know if my computer would allow me to get that PSU and that GPU?

(As you can tell I'm new to upgrading computers...)

 

[Will Baggott]

I have the money already, but I don't really want to sell my CPU or motherboard (Unless the motherboard isn't compatible or something)