You could always use an Athlon 64 FX 53 instead...

Get new fans, or a new laptop. PearPC will most liklely always use 100% of your CPU resources since it's such a CPU intensive program. If you get a P4 with Hyperthreading, it only uses up 50% on each virtual CPU, but I doubt the power usage is much less than 100% of a non-HT P4. Anyway, don't expect...

You mean use Nero to make an ISO file with the update in it? Yeah, that should work fine. I use WinISO to make any ISOs I need though, much more flexible.