With rare exceptions, all such programs are more likely to impair performance than improve it. Informed users have known this for a long time.

These programs are based on a faulty understanding of how RAM is used on modern computers. It is nothing like it is cmmonly perceived. Free memory is the enemy of performance and all modern operating systems will always attempt to find some use for as much as possible. XP and Vista do an excellent job of managing memory on their own. These programs interfere in this process, with predictable results.

Whatever faults the built in memory manager may have, they cannot be solved by any external program.

Larry Miller
Microsoft MCSA