NFS:Underground is for PS2 at the moment; I think it's safe to expect Xbox and a PC convert. (EA wouldn't miss an opportunity like that)
Check out this really <A HREF="http://www.electronic-arts.com.au/eagames/news.php?news_id=42">good preview read</A> about what we can expect. Here's a critical bit that basically says to expect no NSX.
<I>"The biggest change to the next Need for Speed is that it won’t feature the exotic cars from Ferrari, Lamborghini, and McLaren. Need for Speed Underground will instead feature "urban exotics"... Drivers can expect the latest wheels from the likes of Subaru, Toyota, and others major manufacturers."</I>
That's too bad... i was really looking forward to crashing the F&F2 NSX.
Another REALLY interesting feature (which reminds me of what i loved in GTA3!!!) :
<I>"The details are nice but Need for Speed Underground completely changes with acceleration. Streetlights, lampposts and anything else on the sides of the road take on a blurred high-speed feel as your focus narrows on the road as your speedometer climbs ever faster."</I>
Here's some new <A HREF="http://www.nd4spdworld.com/?section=nfsu&page=screenshots&nr=1">Screenshots</A> and more <A HREF="http://www.nd4spdworld.com/?section=nfsu&page=screenshots&nr=2">Screenshots</A>.
Here's the <A HREF="http://download.jucaushii.ro/files/trailers/NFS-Underground_trailer_E3-2003.zip">NFS : Underground E3 Trailer</A> Akira3D mentioned. [9MB, Quicktime]
I think GT4 still looks like it will satisfy us NSX freaks the most.