Project 03: Love-o-Meter -- temperature formulas seem wrong?

seems like this is the issue here:

for one - the project in the book uses the 5V reference...

this means ( correct me if Im wrong here! )

that we are using the TMP36's ready range of .1 to 1.7V and dropping that into a full 5V range... meaning our ADCs are barely using half their range for 1024 steps!! this would make the temperature reading very inaccurate... no?

it would be better to make the reference voltage something like 2V ?? then you are better mapping the potential values to the available bit depth of the 10bit converters?

now I want to make a more accurate voltage reference... and this guys article shows how - I will be trying this next...