Buying a pc off craigslist

Solution
That's pretty outdated, unless they only want like $100-$300 for it, I'd skip it. Heck, here's a build for a little over $500 that would be far more powerful.

PCPartPicker part list / Price breakdown by merchant

CPU: Intel Core i5-4430 3.0GHz Quad-Core Processor ($178.20 @ Amazon)
Motherboard: MSI H81M-P33 Micro ATX LGA1150 Motherboard ($37.99 @ Newegg)
Memory: G.Skill Ripjaws X Series 8GB (2 x 4GB) DDR3-1600 Memory ($49.99 @ Newegg)
Storage: Seagate Barracuda ES 1TB 3.5" 7200RPM Internal Hard Drive ($48.00 @ Amazon)
Video Card: EVGA GeForce GTX 750 Ti 2GB Video Card ($134.99 @ Amazon)
Case: NZXT Source 210 (Black) ATX Mid...
What is your budget?
You should just build your own rig man its very enjoyable and also works out cheaper than buying a pre built.
The PC in the post is quite outdated and you will probably be disappointed.
 
That's pretty outdated, unless they only want like $100-$300 for it, I'd skip it. Heck, here's a build for a little over $500 that would be far more powerful.

PCPartPicker part list / Price breakdown by merchant

CPU: Intel Core i5-4430 3.0GHz Quad-Core Processor ($178.20 @ Amazon)
Motherboard: MSI H81M-P33 Micro ATX LGA1150 Motherboard ($37.99 @ Newegg)
Memory: G.Skill Ripjaws X Series 8GB (2 x 4GB) DDR3-1600 Memory ($49.99 @ Newegg)
Storage: Seagate Barracuda ES 1TB 3.5" 7200RPM Internal Hard Drive ($48.00 @ Amazon)
Video Card: EVGA GeForce GTX 750 Ti 2GB Video Card ($134.99 @ Amazon)
Case: NZXT Source 210 (Black) ATX Mid Tower Case ($34.99 @ Micro Center)
Power Supply: EVGA 430W 80+ Certified ATX Power Supply ($34.99 @ NCIX US)
Total: $519.15
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-05-16 00:24 EDT-0400
 
Solution
I just looked at it... he's asking WAY too much, plus admits a couple of ports don't even work on it. In addition to that, there is no mention of Windows. So that means he's probably either keeping the copy of Windows used on it as well as the serial key... or it has a bootleg version of Windows. No HDD sizing info, either.

What you should do is list what your budget is. If you go the route of building your own here is a guide to building your own with either a $300, $600 or $1200 dollar budget.
http://lifehacker.com/5840963/the-best-pcs-you-can-build-for-600-and-1200

Another possible route you could take if you don't feel comfortable building a system would be to go to a place like Costco. They have a BRAND NEW Gateway computer on sale for $300. You could get that and then upgrade/install a new Graphics Card later on.
http://www.costco.com/Gateway-DX4375-UR22-Desktop-|-AMD-A6.product.100159186.html

Best Buy also has a few desktops at around the $300 mark, too.