I've tried a load of wired and wireless gear and I've never had an issue with the Asus A8N SLi even with the amount of drives I have connected to both the nvidia and Silicon Image SATA controllers.
The only issue I have had was the power issue where if you rebooted the PC it would not load until you reset it again. A simple BIOS update to the revision 007/008 fixed that fine.
Please if your thinking of getting an nforce4 based system,
DO NOT SKIMP on the power supply.
THIS is the most important piece of kit in your system. If you use a cheap and nasty PSU thats a garish colour and costs approximately 25 pounds for a 600w rated PSU then I recommend you take 5 concrete blocks and secure them to your PC and throw it into the nearest canal. It will be more fun than watching your PC BSOD, crash and loop due to low quality power regulation.
Secondly, Once you've got the PSU, make sure its 24 pin ATX with if possible Serial ATA and PCI-E power connections (if no PCI-E power connections then adaptors are available but these need 2 molex connections from different cables/channels)
Now if you get the Asus motherboard - DO not panic when you open the box and the serial ATA driver discs are not there. Simply set the PC to boot from CD-ROM and insert the lovely freedos bootable CD that Asus have supplied to create the floppies required for the serial ATA drivers when installing windows.
Other than that - the only other problem at the moment is the nvidia firewall management software will not install at all ( I've tried 5 discs and 3 different systems ) but I've notified Asus and they know about it and hopefully we will have a working version shortly