When it comes to computers, I have 4 primary concerns:
- quiet ... computers are like kids, and should be seen, not heard!
- ability to use lots of eSATA and USB devices (aka hard drives and DVD burners)
After my desktop system imploded last fall, I spent the winter building a powerful new Skylake for about $1.5k, and I can do anything I need and want now. It runs very cool, and is so silent that I can't tell if it's on most times.
For you, I'd say noise and heat are the primary concerns.
My need for speed is mostly for restoring video with complex filters, and the drive connectivity is to deal with the associated data resulting from those tasks.
I have a Mac mini, but it's the wrong tool for video work -- especially ripping/burning for DVD hobbyists, or even simple things like easily removing commercials or extracting DVD recorder discs. It's small, silent, and fast, yes -- and works perfectly for my specialized needs.
I also have a laptop running Windows 7, and it serves as my main internet PC. But the fan noise often annoys me. If the CPU hits 25%, it starts to whir like one of the model helicopters. So be warned, laptops can be noisy, and often are. It wasn't bought for this purpose, being one of my pre-MS/pre-2012 purchases. I got it for traveling that never happened. If I ever found something small (to fit on desk) for under $500 total (including Windows 7 license), of comparable speed (i7), I'd strongly consider putting the lapatop in a drawer.
Be careful about Windows 8 or Windows 10. They're not much fun to use. My new system has Windows 7 installed. At worst, I could use Windows 8.1 if needed, but not Windows 10. Every new Windows makes more older software break and stop working. For the tools we use, that's not good.
These days, most CPUs meet your needs. Anything 4gb or higher for RAM is probably fine. The biggest RAM-eater is opening lots of tabs in a web browser at once. For example, I often have 25-50 open, and at most, that eats 25% CPU and 1.5gb RAM.
I was looking at Woot! yesterday, and saw some tiny PCs for under $225.
Those are now gone, but Amazon has some: http://www.amazon.com/Pavilion-Deskt...7863096a644bb0
I find tiny PCs very interesting.
Another option is those all-in-one systems they have at Best Buy, where everything is kept in a monitor, like Mac. I'm not sure what you have right now, but those are generally silent and fast as well.
My point with the last two items was to show you that the old days of a big box on the floor/desk, with a monitor attached, are over. Big boxes are usually noisy and hot. We have some interesting options these days. So no more pumping up the AC several degrees, and needing earplugs to concentrate on an important letter.