As long as it uses an i7 quad+ core with HT, has at least 8+ GB memory, at least 1280+ x 900+ resolution in each dimension, a nVidia 330M+ graphics card with at least 1 GB VRAM and at least 2 separate 7200 RPM SATA disks or better and a eSATA port, you can use a portable.
Sager and Clevo make nice notebooks, starting around $ 4 K and ending over $ 10 K for a DTR.
This is assuming that somewhere in the future you will upgrade to CS5 and don't want to throw your investment away when doing so.
The Asus N71 is not powerfull enough.
i'm in no lucrative action , and "small" budget !!
my computer : intel q9300 / one dd 500g/7200 tr/mn + external dd ....it's not a jet, but it works ...
i'm looking for equivalent solution with a notebook between 1200/1500 € ...as possible ...
Have a look here: http://ppbm5.com/Benchmark5.html and notice where all the laptops, with the exception of a Sager end up. Also notice where a Q9450 (faster than your system) with an SSD and two extra disks end up in the ranking. 9 times slower than a fast system and you can assume that your own system with slower disks, will end up at being around 30 - 50 slower than a fast system, if properly tuned. Then a suboptimal notebook will likely end up at being around 50 - 80 times slower than a fast system
Is that worth the money?