mom just bought a sharp LC-32SB24U question about conversions

[bigwayne3000]

ok so my mom just bought my dad a sharp 32" lcd 720p tv set model #LC-32SB24U. is it worth getting a bluray (looking at the cheap insignia ones) player for a 720p tv set? now from what i can understand lets say i have a ps3. i can set that ps3 to put out as 1080i and some tvs will automatically convert that 1080i signal down to 720p giving you a better pic than normal dvds. is this the same for blu ray players? can i set a bluray player to put out as 1080i and have the tv down convert to 720p? also from what ive heard is if the tv doesnt down convert a 1080i signal down to 720p than it just plays it at a normal 420 resolution. in your opinions would it be worth getting a bluray player for this specific tv? my mom bought an upconverter player for like $75 but an insignia bluray player i found for around $150ish is it worth the extra $75?