For linux, you need an ABSOLUTE MINIMUM of 512Mb RAM or you will spend half your life cursing. X-windows, Mozilla, OpenOffice etc are huge memory hogs, to say nothing of your IDE and your own java apps. It seems most linux apps also still have serious memory leaks - and since laptops tend to be rebooted much less frequently than desktops (because you usually suspend instead) this becomes a much bigger issue.
(or you can just stick to using one application at a time ;)). Linux distros tend to have very very bad virtual-memory management…it’s easy to install a distro and end up with it swapping every app to disk “pre-emptively” so that if you leave your laptop for half an hour EVERYTHING is swapped to disk and it takes literally 5 minutes waiting before you can type - everything has to be pulled out from disk one-by-one :(.
Dell + nVidia laptops have historically had appallingly bad support from the two manufacturers. However, Dell’s laptops usually have the best value-for-money hardware (not as good hardware as IBM, and to a lesser extent Toshiba, but considerably cheaper!). Note that Dell make an absolute fortune on selling you minor spec upgrades - e.g. they used to make most of their profit on the RAM they sold for your laptop. Instead of buying a laptop with 512Mb RAM, you could buy the same one with the 256 option, and order 1Gb Dell laptop RAM for that laptop from crucial.com AND STILL SAVE $50! So look at the prices of all the components carefully - some are good, but most are a ripoff (they know customers will expect to be getting a discount for buying it all in one go, and they use this to rip them off).
For the graphics, note that X-windows has traditionally never supported the GeforceXGo (laptop versions of the GF cards) - although they may finally have fixed this within the last 6-9 months since I last checked. So you are stuck with nvidia’s drivers. And, unfrotunately, nvidia has had historically very bad support - like a 3-year-old “official” known-bug that means you cannot suspend-to-disk in X-windows - the nvidia driver will crash linux either then or at resume. HOWEVER in the last 18 months their support for linux has become a LOT better, so although you iwll probably hear many horror stories from nvidia laptop owners probably most of it is now invalid - given how much things have improved in their whole attitude to linux, I would probably get anothe G4Go quite happily (although I would then go psycho if I found that the same kind of critical bugs were knowingly not being fixed! ;)).
Finally, a note about upgradability: nv has recently announced a new format for laptop grapihcs cards that will enable you to upgrade them! The idea is it’s like a “mini PCI”, a small form factor where you can just go out and buy the next GF when it comes out and upgrade your laptop. Obviously a great idea for them and us - they get to sell many more cards (laptops are one of the few large markets they haven’t yet fully exploited), and we get some future proofing. If you can wait 6-12 months, it would be worth checking how soon those laptops are coming to market.
I got my laptop about 3 years ago, with a GF2 in it. I was specifically looking for a system where I could do games dev. OK, so it has a measly 16 Mb Ram on the graphics card - but it has vertex shaders etc, which means it’s still capable of doing all the major stuff for the vast majority of games. From this perspective, assuming you get the non-upgradable card, I believe that performance is almost irrelevant to you - it’s features that matter. You don’t care that you can only do 60 fps in 18 months time on a top game, what you care about is that you can still display all the different features of the game (i.e. how bitter would you feel nowadays to have a GF1 laptop, where you can’t view any shader-effects at all! :().
