It probably all depends on the game, but you can expect that from viewing a PC on a TV (unless it's HDTV).
In Windows you can decrease your resolution (in fact, I would recommend download a program like PowerStrip and decreasing it to 640X480).
On top of that you can increase your Windows font size. This is done slightly differently in different versions of Windows but you should still find it in your desktop properties.
As for text inside games, that would be up to the game. Again, try decreasing the resolution as far as possible. Don't be afraid to show it at something as low as 320X200, either. A regular TV screen can't really handle better than that, anyways. Most games that I know of don't allow changing font sizes, but they do let you change the resolution and that can make a huge difference.
As an added bonus, you might find your games runnign smoother, too. Good luck. Sorry I can't help more than that.