Literal, fanboyish answer: "Buy a Mac Pro or Mac Mini and stick it under the table and use whatever monitor/keyboard/mouse you want."
Practical, not-as-fanboyish answer: I'm guessing that your aesthetic taste varies from mine (since I like how Mac's tend to look.) In that case, I'd say "don't buy a Mac." Apple chooses to bundle hardware and software. Thats their decision and pretty much their bottom line; use it. Or don't.