If you want power, the SC is the cheepest way to get it.
For 2002, the difference - in dealer invoice price - was $1200. Not only do you get an SC, but the engine is built up, the ECU is tuned for it and you get upgraded rims, a polished exhaust tip, etc.
That's quit a bit of value. After drving an SC Xterra, the choice was easy for me
And that's what it boils down to - whats going to make you happy? If I were you, I would definetly drive both. I know budget car rentals has Xterras - that's where I rented to test out which X I liked best. I went from originally wanting "just" an NA automatic to an SC 5-speed, and now I couldn't be happier with my choice.
If your going to change cars every two years, then it probably isn't as big a deal - me, I keep vehicles for 5-7 years. Since I bought the X new, I intend to keep it for even longer - so I wanted to make sure I would be happy for the long haul.
Also, make sure you read a site like
http://www.carbuyingtips.com and take it's advice to heart...