Buy.com has the Kingston ValueRAM 2GB DDR SDRAM memory module desktop memory kit (model no. KVR400AK2/2GR) priced at $44.99 which is around $15 less than the lowest price we could find anywhere else, plus until 12/17/08 save an additional $5 with this mail in rebate offer that drops the price down to $39.99 with FREE shipping.  Sales tax applies for residents of New York and California. 

This 2GB memory kit is also available at TigerDirect.com for $59.99 with $1.99 shipping.

The Kingston ValueRAM desktop memory kit includes two 1GB, 184-pin DDR SDRAM memory modules.  It is backed by a lifetime limited warranty on parts and labor from Kingston.