Summary: I'm very pleased with my Dell Inspiron 6000d. I have SuSE 9.2 running on it, with kernel 2.6.8. [Updates: SuSE 9.3, SuSE 10.0 with kernel 2.6.13, SuSE 10.1 with kernel 2.6.16.] All systems are working well under both Linux and Windows, with just a few exceptions. In particular, wireless networking with the Intel Pro/Wireless 2200BG card is fully operational. (It's recommended to get the latest driver version.)
However, early adopters will have to wait for a few features to be properly supported in Linux. Outstanding problems as of 2005-03-30 [updates 2006-02-20] include:
The ATI Radeon M300 graphics chipset is supported by Xorg-X11; but its Radeon driver does not yet support direct rendering (3D graphics) for the newer chips like the M300. There is, however, a proprietary ATI driver that can do direct rendering. Follow the link for a reference and for caveats. If you're getting an Inspiron 6000 with Intel graphics, do some web research to see if the problem reported here has gone away.
The primary disc outperforms any of my desktop systems in disc benchmarks. The Intel 915PM chipset includes a disc controller that can handle both SATA and UDMA (PATA), and in SuSE as with most distros, the SATA driver (ata_piix and friends) is loaded in an initrd. Suspend to disc (software suspend) has to be done very carefully in that case: you can't resume from the disc if you don't yet have the driver. Suspend to disc works starting with SuSE 10.0, but for kernels earlier than 2.6.13 you'll need to create a custom kernel with ata_piix and its dependencies hardwired.
Similarly, [in kernel 2.6.8, SuSE 9.2] you can't turn on DMA for the optical drive due to a bogus conflict with the SATA driver. People have been living with this for years, for readonly applications, but the lack of DMA really messes up burning discs. These issues are generic for any laptop, desktop or server with an Intel chipset and a SATA controller (even if the primary drive is not SATA), not specific to the Inspiron 6000d. Kernel 2.6.13 in SuSE 10.0 has this fixed -- the developer works for SuSE and there is the possibility that the fix is a special patch which may not be applied in all distros.
The card slot for Multimedia Card - Secure Digital memory has a new kind of controller chip and the driver is only available in the latest kernels (tested in 126.96.36.199).
I found very lively discussion and a lot of good information on the mailing list firstname.lastname@example.org. There is also email@example.com, which is in German.
The experiences of other Inspiron 6000d owners, and other types of laptops, can be found through links on Kenneth Harker's page, http://www.linux-laptop.net/ (now redirected to http://www.linux-on-laptops.com/ sponsored by LinuxCertified Inc.)