I would give similar advice of repairing/reinstalling the OS or SSD upgrade, but another option if you're set on a new PC would be to recycle some of your existing components into a new machine and build your own. You could use the following:

Memory 8192MB (4x2GB) 1600MHz DDR3 Dual Channel
Video Card AMD Radeon™ HD 7570 1GB DDR5 Graphics Card - Assuming its PCIe
Hard Drive 1TB Serial ATA (7,200 rpm)
Optical Devices 16x DVD +/- RW Drive (read/write CD & DVD)

If you're to go down the route of building your own PC, you'd need a case, motherboard, CPU (I5 would be fine), few case fans and PSU. Would advise as Dave said, get a SSD as your primary drive and use the 1TB drive as your repository. If you get a decent case and PSU, you can upgrade other parts in a few years at your leisure.

Considerably cheaper than buying a new PC (very easy to assemble), only downside if any component goes you'll have to chase the particular manufacturer for replacement.