I would try best buy. The personal are very helpful and can point you in the right direction. If not they can find someone who can. They also have the GEEK SQUAD to help.
The quickest place to find a Dell Inspiron power supply may be on Amazon. You can also contact your local Dell supplier and ask them for their assistance.
It tells the motherboard that the "Power is Good". PG stands for Power Good.
The best power supply I've used is the Hurricane digital power supply, it has many features my favorite being that it remembers your last settings.
The power supply's power-good signal prevents a computer from operating on improper voltages and potentially getting damaged. Typically, a computer will only start up after receiving the power-good signal.
The OCZ StealthXStream is a great camping power supply.
I do not know what the motherboard you have so your question is a good one. Find someone in your neiborhood who has the same motherboard as see what power supply they use. The other way is to fit one of the power supplies to the motherboard and see if it catches fire
You can find the power rating of your power supply by looking at the label or sticker on the unit itself. It should indicate the maximum power output in watts (W). You can also check the manufacturer's website or product manual for this information.
Hipro is good
There are quite a few places you can go to get a DC power supply. For a good discount go to www.creativesavings.media.officelive.com and join their saving network, then shop through thier mall to find discounts from Radio Shack and Newegg.
Good power supply and good cooling.
http://www.nextag.com/uninterruptible-power-supply-ups/stores-html This website compares prices and specs for UPS. Use it as an idea for prices, as you can search around locally to see if you can find any good deals as well.
Amazon is always a good place to start for items like a programmable slow cooker. You will usually find that there are a range of prices available from the Amazon "market place". If nothing else Amazon will give you an idea of the make and model that you might want, once this is known then you can further hunt for a good deal on sites like eBay.