• Always have a spare/backup PC.
• Use a KVM switch.
• Always network your PCs together.
• If you access the Internet use a hardware firewall.
• Locate your office in a room with a least one window you can look out of.
• Don't be a troglodyte.

First, if possible, place the two PCs (you're following our advice aren't you?) next to each other and use a KVM switch. Linksys and IOgear, among others, make excellent KVM switches. A KVM switch allows you to use a single keyboard (K), monitor (V) and mouse (M) to control as many boxes as it has ports. A KVM does not, however, obviate the need for networking (even though KVMs are considered to be networking gear). The network is there for Internet connection and file transfers (as in backing up one PC to another).

If possible, have a window you can look out of so that you can periodically focus your eyes on brightly-lit, far objects. Also, have a timer that you will set to remind yourself to get up and walk around for a few minutes at least once an hour.

But most importantly, do not forget social networking. You do not want to become a troglodyte. More business opportunities can come your way from face-to-face contacts than from any other method.