The following are my experiences with the Dell Latitude C400 Laptop computer and Linux. Some information is shamelessly stolen Manuel Chakravarty's considerably more competently written website.
In short, this is an amazing laptop with one serious problem that almost makes it a showstopper for linux users -- The onboard Intel i830M uses system memory for graphics operation, and the BIOS only allows for access to 1MB of this without special driver code. This limits you to 1024x768x8bit or 640x480x16bit. No workarounds yet. Some people have tried some pretty elabourate things, but without luck. In addition, the server will usually crash the entire console subsystem if you ever try to exit it.
To even get to this crappy support, you need to update to a 2.4.x (x > 11) kernel, update to XFree86 4.2.0, and fiddle with a few other things.
I almost despaired and assumed that this would simply be a Winders only machine (shudder), until I stumbled across Xi Graphics' web site, www.xig.com They have a driver for this computer, and amazingly enough, it works like a charm. In fact, I downloaded the tar, ran two RPM commands, and had 1024x768 up and running within 30 seconds. All this with stock RedHat 7.2 (Enigma) Linux. Am in the process of testing out KDE 2.2.2.
Only downside: Xi's drivers cost money. However, 69$ USD to get the laptop working and useful again is worth it to me.
It is possible that Dell will get a clue and release a new BIOS version for this laptop with 8MB of stolen memory, but until that happens, you might be stuck forking over the extra dough.
A few people have reported a couple of problems with the Xig drivers:
I just tried upgrading to SuSE 8.1, the latest and greatest version of SuSE. It detects the graphics, and happily runs at 1024x768xfullcolour .... ONCE. Try to exit the server, and the screen/keyboard will lock.
As of yet, the Xi Graphics Summit_LX server does NOT work with this configuration. I am working on solutions, as I'd much rather use SuSE on the laptop.
BTW -- SuSE Setup finds all other hardware on the machine sans problem.
I knew about this some time ago, and just didn't get around to trying it: to get X working on SuSe 8.1, you just have to make sure that the FBConsole isn't running ... All I had to do was remove any references to vga=XXX in the boot manager prompt. You can update /boot/grub/menu.lst to completely get rid of this for good. No problems. Sweeet!
Most people are reporting that XFree86's latest live snapshots are working great with this laptop (i.e. you prolly won't need to buy Xi's server any more) and 4.3.0 should support it great right out of the box. Please note, however, that I do NOT run stock XFree86, and still run Xi Graphic's Summit LX. I have no idea how well the new XFree86's really do work on this laptop.
Mail to: mw@lanfear.com