Geiser093 
If you want, you can shoot me a PM. I refurbish a lot of systems, and build plenty of new ones too. I can go over pricing and what I can offer if you'd wish. Here in the open forum, I can offer some basic tips, though:
I would go refurbished. I've owned many computers- only one of them was brand new when I started owning it (I built it in 2007, and still use it today). Go for a Core 2 Duo processor for minimum, but if you can spring for it, a Quad will be nicer. Go with 4GB of RAM minimum, and get a 64 bit OS so you can take more. Go with a larger hard drive (250GB or larger), and you'll be good to go.
I'd stick with Windows 7. It's supported until January of 2020, and will likely receive the free upgrade to Windows 10 when it comes out.
If you want a new system, here's my tips on what to go for from building them:
Go with an AMD CPU. A 6-Core 3.5 GHz AMD CPU costs $110, while the same speed and cores on an Intel CPU costs $579. The AMD is no slower in my experiences. It's just a much better deal. You're paying for the name. 90% of the new systems I build are AMD-powered. It's well worth the savings.
Go with a hybrid SSD. They cost more than a regular hard drive, and aren't as fast as a true SSD, but they're faster than a regular HDD, and a lot cheaper. They're the best compromise.
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I do have a horse in the race of course, but I'd personally go refurbished. I run an eBay store and handle the photos for it from a refurbished tower. I design websites and do movie editing on the computer that I built back in 2007 (Actually older than my refurbished desktop in the office). The money savings are well worth it. My PC in the office will let me run an online radio station while editing photos and uploading to my FTP. That's plenty for me.
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