Jeremey-san :
My current system has a Nvidia GeForce 9800GT i would assume that's worse than the two cards im asking about right?
Thanks everyone!
EDIT: I would prefer a rebuilt system i have never put one together and would just rather it be prebuilt like a dell or something if that matters plus i have a $500 dell voucher which is what made me start looking there.
The 9800GT was high end 2008. The GT 640 is med-low/low 2010/2012 so they're actually comparable. I'd expect at most a 50% improvement. If you just put a little more towards graphics, it'll get A LOT more done.
I totally understand your sentiment for wanting to use your Dell voucher and not build a whole system yourself. But there are three things you need to consider:
1) Dell is going to put a terrible power supply in your computer and it will be dangerous to run a graphics card with it.
2) Dell will charge you at least 150% of what a graphics card should cost if you buy it from them.
3) It's easy to replace power supplies and graphics cards with just a phillips (+) screw driver. You just need to remember to connect it everywhere the original one was (motherboard, CPU, hard drive, fans, graphics card).
Since you've already got $500 there, I agree with sticking with Dell. So let's find you something that suits your needs that we can drop a $40-$60 reliable power supply in (read "reliable" as Antec, Corsair, Seasonic, or XFX) and add a graphics card into. It sounds to me like your monitor is adequate for now, so we'll just be looking at your tower and these two extra parts.
I assume you mean $1000 including your $500 Dell coupon? And does the normal Dell website ship to Canada or should I be looking at Dell.ca or something?