Probably not. For 1) it probably won't work at all unless you raise the timings of your OCZ to equal the timings of the generic ram and even then it might not 2) You'll lose your ability to run the ram dual channal because it will no longer be balanced 3) Raising the timings will slow the OCZ down which will slow down aspects of your current performance 4) If you are overclocking you can kiss your stability at that level good bye.
On the other hand, an Extra half gig capacity will help out with a few games. It's not a total not brainer, but be prepared that it might not work and it may have an aggregate impact on performance that is negative.