Cetro,
Try looking <a href="http://www.nsxprime.com/FAQ/Reference/comparisons/porsche.htm">here</a> in the NSX FAQ for comparisons between the 993 and NSX.
Also, there have been numerous message threads in the past on this subject such as <a href="http://www.nsxprime.com/ubb/Forum1/HTML/000800.html">this</a> one.
Personally, I prefer the styling, rarity, and seating position of the NSX over the Porsche.
Also, I've noticed when parked nearby Porsches in a parking lot, my NSX is likely to get more attention than the Porsches. Maybe it's the rarity (Porsches are common around here) or maybe it's the NSX's Ferrari-like looks? I dunno, but I'm not arguing with it!
The NSX supposedly offers superior reliability. I've had my '91 NSX for almost a year now and put 7,000 miles on her. Not a single thing has gone wrong with it-- pretty good for a 10 year old sports car! I've heard far too many horror stories about Porsches with respect to reliability, though I've never owned one myself.
I know there's other forum members here who own both. Maybe they can provide some better information for you.
[This message has been edited by BB (edited 01 June 2001).]