That's it. High power consumption and high temps. I'd say go with the 480 anyhow. The performance trade-off is worth it. You'll be able to crank up the details, AA and tesellation. Because the 460 is also a good card, you'll be able to sell the 460 easily or use it in another system.
You can get Hardware Monitor (HWmonitor) from http://www.cpuid.com/. There are other tools too, but this one gives you temps for all your components on a single screen. It's a decent tool for getting a good idea about your heat situation. It's a pretty standard tool a lot of people use to measure temps.