VGA: nVidia -- ATI makes good hardware but their Linux support is not going to improve for another 6-12months or so[/q]
I run a Radeon x1900 GT and it works just fine with AMD's Linux drivers. The support is pretty good- the only thing that I know is messed up is the YUV overlay setup that MythTV and TVTime use. If you don't use those apps to watch TV on your computer, you're fine. The big gripe with most people and ATi Linux is that the cards don't perform nearly as fast as NVIDIA's. My x1900 GT is faster than an NVIDIA 7900GS in Windows but runs about even with a 6600 in Linux.
[q]Board: A Linux friendly motherboard
http://www.phoronix.com/?page=phoronix_articles look under motherboards[/q]
Phoronix is a good source for Linux-specific information, so is linuxquestions.org. Just about any NVIDIA-based motherboard will be fully-functional under Linux. Intel boards work well, except that the 965 series chipsets have no native PATA support and older kernels don't support the commonly-used JMicron PATA chip. ATi boards work well too, with the exception of the Xpress 200M, whose integrated graphics give Linux users fits. The CrossFire boards have been reported to work well. I haven't used SiS or VIA boards in a long time and can't comment much on them, but most things (USB, SATA, PATA, PCI, PCIe) should still work because they are standard devices to all OSes and use generic drivers. Ethernet should be similar as well. It's generally just the sound on the uncommon boards that can sometimes have trouble working.
[q]RAID: 3Ware or LSI - non-hardware RAID not recommended[/q]
Not true. Linux has
excellent software RAID support using md. It's usually much faster than all but the most expensive hardware RAID controllers. What's not recommended is running a RAID using just the motherboard's onboard SATA ports with md as the onboard ports can't handle the simultaneous accesses that an array will put on them. Getting an external PCI Express SATA controller will alleviate this. I use HighPoint's RocketRAID 23xx series PCIe controllers as they are much less expensive than 3ware/AMCC, Intel, and Areca hardware RAID controllers and the PCIe bus can handle boatloads of traffic. The 23xx series use Marvell SATA controller chips and HighPoint has released the driver as open-source. The 2.6.20 kernel has the 23xx driver rolled into the sata_mv module so no external driver is needed for newer kernels.
[q]Ethernet: Broadcom Corporation NetXtreme BCM5754 Gigabit Ethernet or RealTek RTL-8169[/q]
I have a Realtek 8169 as sold as a Netgear unit (GA511 or something like that.) It works quite well. I'd also recommend Intel's PRO/1000 adapters as well as they work well and have good Linux support. But just about any Ethernet interface will work, including the onboard interfaces on most new motherboards. NVIDIA's integrated GbE is particularly good as it's PCIe based.
[q]WiFi: do not use it but if you do anyway
http://www.aircrack-ng.org/doku.php?id=compatible_cards#tutorialis_my_wireless_card_compatibile
http://madwifi.org/wiki/Compatibility[/q]
Intel WLAN cards are particularly good but they're only sold for mPCI and mini-PCIe for notebooks IIRC. Atheros (some D-Link units) has the pretty decent madwifi drivers and Broadcom cards are pretty spotty as far as wireless goes. I use a wireless bridge for my desktop- Buffalo WLI-HP-TX4. I plug an Ethernet cable from my desktop into the back of it and the bridge will convert wireless into Ethernet. It is much more powerful than a PCI wireless card and saves the headaches of missing drivers for WLAN cards.
[q]Sound: SB Live! or Augidy ( the X-Fi does not work ) or other compatible card[/q]
Most onboard sound is an AC'97 derivative on older boards like my NForce4 or the Realtek or Intel HDA on newer boards. Both are supported in Linux.
[q]For games check out WINE and Cedega and this review:
http://www.phoronix.com/scan.php?page=article&item=681&num=1
http://appdb.winehq.org/appbrowse.php?iCatId=2
http://games.cedega.com/gamesdb/
http://qemu.org/
http://www.linuxquestions.org/hcl/index.php
GL :-D