400 MHz DDR would be very much overkill. Remember, the chipset’s only rated to 266 MHz, albiet dual channel (for 533 MHz of effective bandwith). Also keep in mind, the Tyan board will need to be overclocked via a third party utility as the BIOS offers no options (but it still shouldn’t be hard to find one, either). Remember, this board will offer you more performance without an overclock than an overclock to, say, 3.33 GHz or even higher due to the extreme bandwith offered.
Probably your best bet to save some money would be Crucial or Kingston, both of which offer 333 MHz RAM at sizes up to 512 Mb, and Crucial even offers 266 MHz at up to 1 Gb densities. Oh, they both have lifetime warranties (which does matter to some degree, and they’ll usually not ask any questions, either). 333 MHz RAM will give you more than enough headroom to OC, and you’ll also be ready for when Intel shifts to boards supporting a 667 MHz FSB with dual channel 333 MHz DDR. Kingston also offers 400 MHz DDR SDRAM at 512 Mb sizes, giving you headroom for Intel’s move to an 800 MHz FSB sometime early 2004. As a suggestion (and one I use even in a non-OCed system), RAM can throw off alot of heat, especially if you have all 4 DIMMs populated. CompUSA sells, believe it or not, the same RAMsinks (actually just heat spreaders) used by Mushkin on their special high-clock DDR SDRAM DIMMs, for about $15 apiece, and with the same 3M adhesive thermal compound. Since you’re saving nearly $100 on each DIMM anyway going with either Crucial or Kingston, this is a small addition that doesn’t add much for performance but it does increase stability when really laying into the RAM.