I am not a true scientist, but I would look into a server. Either a Xeon or a Opteron. The current SB CPU's are low grade, or not the top performance. i would wait until the LGA 2011 CPU's or Bulldozer have been released. There you could decide server or desktop.
As a 'scientist', I would work on servers, due to the fact I can bundle stations for faster more advanced calculations per second, and storage as well
On straight numbers:
Core 2 Q9550 - 2.83 GHz (2x6MB cache... this was a 2xdual=quad design, not a true quad core like the i7s...so some core to core transfers are slower for C2Q)
i7-2630QM - 2.0 GHz turbos to 2.6-2.9 depending on number of active cores, 6MB cache, 'true' quad-core with hyperthreading (8 total threads)
Most reviews are putting the 2nd gen i-series about 15% over the comparable 1st gen CPU... so perhaps it would behave like 2.3 GHz 1st gen i7. This doesn't directly translate to a C2Q. The 2630QM runs at roughly 60% the clockspeed of a i7-2600 and has generally the same architecture (2600 does have 8MB cache)... you could guess that you'd 60% of the +80-100% performance... giving you roughly +50-60% above your current CPU... Maybe a little less due to the lower cache amount. That's a big 'guess'. You should see an improvement... I just have no way to confirm that.
I can't say whether a server is a better option (could have a relatively 'dumb' laptop connect to server for classroom demonstrations perhaps?).
Just thinking things out with the numbers provided. I hope I didn't confuse things *too* much Good luck!
How would what jpmucha said transfer to single threaded apps? I read that 2630qm is faster, is better than some desktops, but I think the statements are related to it's multiple use of cores.
How do you estimate it to perform at 2 ghz single core vs 2.53 ghz first gen such as i5 460m - in single thread apps/games?
Besides that, I'm guessing that it will be slower than let's say i7 2620m or i5 2540m in single threaded apps which have higher clock rates? Or am I wrong to think that?
I have a Q9450/8GB DDR2/GT460 2GB desktop (@2.66 Ghz), just got i7 2630qm/8GB DDR3/GT540m Dell laptop. I did a few benches and tests, on the same monitor resolutions (laptop connected to external display). Long story short, laptop is 1.6-1.9 times faster then desktop, that's it. Note: I'm VFX artist/TD, so all my tests, apps and benches well hyperthreaded, it may be different on single-threaded apps.