I'm not a gamer and I build plenty of PC's for nongamers.
Lack of bloatware and tremendous upgrade ability is what you get when you build your own PC.
You won't save money building your own. But, you won't have the 'ball and chain' of a brand name.
Sorry, I would never buy a desktop dell, HP, gateway, 'insert major computer company name here'. The number of board/powersupply components that I replace on the 'cheap quality' name brands is incredible. And, they fail after the basic warranty expires. And, your memory, processor, graphics, power supply, memory,.... upgrades are very limited. Buying 'major brand' is like visiting jippylube for service.
If you can disassemble and reassemble your desktop, then you'd have no problem building your own machine. A good online store, like newegg has buyer reviews on most products they sell which should help you pick components within your budget.
Computer ATX case with powersupply $30-80(pick one that will match furniture for peace with your better half)
Samsung SATA CD/DVD 20x burner $30 or $35 with lightscribe
winXP-pro $140
Motherboard(socket AM2 or 775) $50(with sound, NIC, integrated graphics)
Processor(dual core) $70
Single stick memory(2gb ddr2) $35
Harddrive 160gb 7200rpm $45
Reuse your mouse/keyboard/monitor! Upgrade those whenever you want(watch sales rebates and closeouts).
I've seen closeout rebated 19-20" LCD's for $160. Keyboard/mouse depends on personal preference for look/feel.
Upgrade to quad core $1000 CPU in a couple years when price drops it to $150. Double memory in the future. Add extra harddrives. Install fancy graphics card for whatever purpose needed(new game titles).