I have a client that wants to play the videos I shot for them on thier computer monitors.....the dvd"s look good when played on a TV...but when played on Computer screens and laptops...its all blurry...what gives...you know?
I have noticed also that even if you play a Blockbuster rental on a computer...it tends to be blurry.
If the TV is a CRT, then that might explain the difference. You might try applying a de-interlace filter in Final Cut before you export your movie to iDVD (Effects>Video Filters>Video>De-interlace).
If I recall correctly, I think FCP 4.5 predated the Final Cut Suite and could be purchased as a "stand alone" application. But if you aquired FCP as part of the Production Suite, then you may also have Compressor and DVD Studio Pro at your disposal. Learning to use them, even at a basic level, should probably result in DVDs of a higher quality than iDVD is capable of.