CyberPowerPC
HP Mini-Tower
ASUS Essentio
Lenovo-ThinkCentre
Intel i7-4770k 3.5-3.9Ghz
Intel Xeon E3-1240V2 3.40Ghz
AMD FX-8300 4.2GHZ
AMD A-4-5300
16 GB DDR3 SDRAM
8GB DDR3
12GB DDR3
2 GB DDR3
DVDRW/CD-RW DL
DVDRW/CD-RW DL
DVDRW/CD-RW DL
DVDRW/CD-RW DL
2TB SATA III HD (7200rpm)
500GB SATA (7200rpm)
2TB SATA III HD (7200rpm)
250GB SATA (7200rpm)
3GB NVIDIA Quadro K4000 GPU
2GB NVIDIA Quadro K2000
1GB AMD Radeon 8760 GPU
AMD Radeon 7480D GPU
4 USB 3.0/ 4 USB 2.0
16 USB ports
4 USB 3.0/ 4 USB 2.0
4 USB 3.0/ 4 USB 2.0
10/100/1000 Ethernet LAN
10/100/1000 Ethernet LAN
10/100/1000 Ethernet LAN
10/100/1000 Ethernet LAN
Liquid cooling system

Bluetooth 4.0

Windows 7 Pro 64-bit OS
Windows 7 Pro 64-bit OS
Windows 8 64-bit
Windows 7 Pro 64-bit
$2199.99
$1435.56
$849.99
$453.53

For a self-employed business person having a company like house cleaning, window washing or landscaping; I would say that a dual core processor (AMD A-4 or Intel I3) would be just fine. Add at least 4 GB of ram and 250-750 GB of hard disk space, and it would be plenty fast enough and have more than enough space. I chose these specifications because; for programs like MS Office, and QuickBooks you don’t need tons of firepower. And the hard drive doesn’t need to be huge because you’re typically only holding client and employee information.

For someone like a Scientist a dual core or a quad core processor (AMD A-8/A-10 or Intel I5-I7) would be a good choice. I would give it at least 8 GB of ram and 640-1TB of hard drive space or maybe have a smaller Solid State drive for much speedier calculations; they could have an external Hard disk drive if they need additional storage. I choose a dual or quad core