20" iMac Core Duo with 1.5GB RAM I have been studying the memory section of iStat Pro as I have had increasing delays in Safari lately (ie. beachballs of frustration). What, in basic terms, do the 4 categories of memory used mean? Wired Active Inactive Free After using the computer, I seem to run very low on free memory. Closing programs does nothting to change this. Rebooting does but that it not a good workaround. Am I really running low on RAM?