What is my minimum system power supply?
I can't seem to figure it out, should I just add the wattage of all the rails or is there any other process?
PSU sticker -
HTTP://imgur.com/6xoUwN7
I don't really know anything much about these PSUs. I wanted to know if it will atleast support a graphic card which requires 19W power supply and minimum system power supply requirement is listed as 300W.Without knowing the rest of the parts in your computer this is hard to come up with a minimum power supply. The one you have is a Dell 250w power supply. If you are GOING to just replace it because of the video card you can go with a 300w.

I normal would go with you can afford keeping in MIND that you always use it again on another machine.

If i were spending money on a vid card i wouldn't trust that PSU for even 1 day...As Spoiler SAYS, we really need to know your system specs, and what video card you want in order to advise whether you require a new PSU and if so, what to go for.
To figure out your PSU's wattage capabilities, don't just add the rails up - look on the label where you have "Continuous total DC power output..." - essentially you have a 250W PSU, with 204W on the 12V rail which is where most of your power draw will be.Sorry for the late post, this is actually an old pc of mine.
Specs are -
Intel Pentium Dual Core E5400 2.7ghz
4gigs of ram (2x2), inbuilt intel (R)  g45/g43 express
1 fan, 300gb HDD chipset. Basic hardware, Webcam, keyboard, mouse.
Basic desktop motherboard, anything else I need to note down? I think my usage will be around 150-200w  I am not sure tho. The graphic card is a low-end classic called Geforce GT 720.
(Thanks for the reply, this is by far the fastest respond I could have got)See Here...http://outervision.com/b/FrrkdM
That's my current usage right now.
So, will that pose any THREAT to this card or should I just dump the machine back to where it was?You'll be just fine with those specs and the GT 720 on that PSU Thanks people.