I converted the cellar in our old house to a cinema setup.
LCD Projector, 5.1, DVD and PC. The screen was 83" and made of an old bed sheet.
Best bit was the local theatre (The original Carnegie Hall in Dunfermline) was getting new seats from a lottery handout, quick email to the manager and I had a row of four 1937 art deco red velvet seats. The whole thing was sound proofed with carpet tiles, and we had an external door, so it even felt like you were going out.
Then got a plumber to put in a proper radiator so it was nice and cosy.
Unfortunately 12 years later when we moved house we had to leave it all behind as it was a selling feature.
Now have to settle for a big telly, it's not the same.