There are things you can do to make your computer more quiet, there are noise dampers for hard drivers, you can switch out the fan for a quieter one, change the CD/DVD driver for a new quieter one, you could buy special liners that you put on the inside of your computer which reduces noise.
But make sure you know what you are doing before attempting these things, for example might a quieter fan have a lower RPM and move less air, thus not offering the same amount of cooling, especially if you add sound insulating foam you need to make sure there is enough airflow so that your computer doesn't over heat.

Newer machines TEND to be quieter then older ones, but it's not always so, and I would make sure to listen to the new machine in use before considering it if sound levels are that important to you.

High noise is not in itself an indicator of problems unless the computer didn't use to be loud.

If you're unsure still, take it to a shop and have them evaluate and show you the options.

I do not have enough information on this candidate.