The symptoms you describe (blue tint on one side of the screen, and blue dots in the middle of the screen) are commonly reported problems from long-term owners of these Sony rear-projection LCD TVs. The problem is usually caused by a defect in one of the LCD panels within this TV's "light engine" - there are some extensive "write-ups" of this issue on the web.
On some of these models, Sony extended the warranty on the light engine to cover this issue. Even though that extended warranty has likely expired on your 5 year old TV, I suggest you first call Sony support to find out if they can still help you out with this problem.
Without warranty support, fixing the problem is probably not worth it given the low cost of a brand new flat panel LCD TV of roughly the same size as your old rear-projection TV.
