2007 macs base spec only included 1G RAM
2008 macs base spec include 2G RAM
for the reasons stated I recommended double - RAM prices vary on a daily basis - but its only about £40-60 for a (crutial/kingston) 2G upgrade, less for a 1G
Do what you want - based on what else I do with my macs, I find the investment worthwhile.....
S