Hey sne35,
These are just my thoughts... hopefully others will chime in...
As my signature shows, I have an AMD64 3200+ (2.2ghz,512kL2). I don't see the issue with temperature. When fully loaded and overclocked to 2.45ghz, high's are 53C, about right for an internal temperature reading I'd guess. The heatsink reaches around 35C.
When you setup up your system, be extra careful when you make-up your cpu to apply heat compound in a smooth, thin layer. Use a good quality heatsink and fan (stock is fine for normal speed or mild OC). And finally when your "up" check in BIOS first thing to make sure the cpu temperature is stable. Allow a little burn-in time for the compound to shape (my preference) and then try some 'shake-out' by booting to Memtest86 and let it run for an hour. If error free after a couple hours, install WinXP, patches, drivers, etc. Next Prime95 and run blend test for a couple hours. If this comes back without errors, and the temperatures from within EasyTune are reasonable you should be good to go.
As far as running a mix of IDE and SATA... hmmm, wonder what the person you were talking with was referring to? I guess my answer would be that it is usually okay to do (I AM!). On this board some folks have found disabling one or the other of the SATA controllers to allow higher overclocks.
In my case, I am using the SATA for a raid0 array 2x36gbWD and a Maxtor 160GB on the IDE. Like you say, it is nice to have the storage space. That is the kind of thing the extra ports are for!
Regards,
Karl