Most computers either have HDMI output or you can get some sort of adapter (at Walmart or Office Depot) to hook whatever plug you have into HDMI on the TV. There may be some audio issues though with some HDMI inputs.
Do you have a TV now? Why don't you try it out first and see how you like the 'big screen' before investing in a new one.
Bigger question is not if you can do this (most TVs make it easy) but whether you should do this