Bill Machrone, long-time editor of PC Magazine, coined a "law" that the computer you wanted always cost $5,000. Which held reasonably true for a rather long time. It broke down maybe about 10 years ago although, as with the latest Mac, you can still get to $5K without too many gymnastics for pro video work or high end gaming.
You can configure a desktop for way cheaper than that and it can run 90% of modern games. Just don't get the latest generation top of the line Nvidia/AMD card, either get the previous top of the line one or a decent mid-range one (check benchmarks when choosing).
Don't get the most expensive RAM or CPU, you lose 10% real performance but you halve your budget.
Windows is fantastically supported: Microsoft Office, Adobe suite, AAA games, Active Directory, databases, browser and browser plugins, and a thousand others.
