It depends on your video card. Most video cards have a DVI port now, which will hook into a DVI or HDMI connector on your TV.
(I Believe) All TV's with 720p or higher resolution have component inputs, but not all video cards have the VIVO port with component out.
If you get a TV with HDMI or DVI, then you can safely hook a computer to it. My Samsung slim-fit HD TV (Tube) has an HDMI port.
In short, yes you can hook your computer into a tube TV. The clarity depends on what TV you get. The Sony XBR tube is arguably better than some plasmas, but it's a beast at like 200+ lbs.
If you're going to be playing video games, get the tube. LCDs and plasmas have a mean burn-in and usually have high latencies.