That's Intel Speedstep, which automatically underclocks your CPU when idling in order to conserve power. It can be disabled in the BIOS as well.
There is no "upgrade CD" that allows you to jump from 32 bit to 64 bit vista, you need to format and start over. However you shouldn't need to buy a CD, if Vista came with your computer you should be able to order a 64 bit DVD from Microsoft, that's what I did. Only costs about 10 dollars. Use
this link to do this, you just need the product key of your OS, which should be on the sticker on the side of your computer.