I played briefly with Windows 8 beta and it did not excite me much at all as a new operating system. The new interface that you have seen pictures or videos of has obviously been tweaked for tablet usage. However, there was not much else that might entice me to upgrade for a PC. Unless there is more features waiting in the wings, I wouldn't be too concerned. I likely will be sticking with Win 7 for a while until something else pushes me to change.
It's pretty light on required specs so it should run fine on an i5. I'd base your processor choice more on what other software and tasks you plan to run on it.
Edit:
If you think your current PC will run it, you can try Windows 8 for yourself without upgrading by using the trial version and
Virtualbox that allows you to run another other OS virtually.
