Yep smitty mate I suspect you may not have run the memtest long enough mate if the problem has gone because it is useless running less than 8 passes I know it takes a long time but for future times mate always let it run at least 8 passes unless you get errors more or less straight away.
Now the single stick of RAM is good but it is always worth remembering that (and I say this from my own personal viewpoint) memory is run in channels that is to say there are two channels that run from the CPU to the RAM and that the memory is more quickly accessed if it done through two channels.
So say for example you have two water tanks (CPU & RAM) and they are connected with one 4 inch tube (one channel) the water will flow ok though the one tube until the next tank is loaded and that takes place at a set speed. However if you have two tubes of 4 inch bore then it follows the second tank will fill twice as fast as the one tube setup.
So the very best thing to have set up is 2x4GB sticks which will use the two channels (tubes) rather than the one channel (tube) of 1x8GB. This of course as I said my own personal theory on the issue and I stand to be corrected of course. Now the trick is when you buy RAM then get it in matched pairs that is to say the sticks will have come from the same production batch and be very closely matched in speed and timings. You can tell they are because the production batch serial numbers will be consecutive.
I am not saying what you have is wrong far from it and I think if you were to get another 8GB and put it in the secondary channel (slot) then you would notice the difference in performance. Just keep that in mind mate for next time but the second stick will need to be closely matched to the one you have in speed and timings .
Now I have you thoroughly confused there is this you might like to use too
USING OPTIMISE TUTORIAL
Just a little something that will make your machine a little faster and more efficient is this
Optimize Windows 7 - Windows 7 Help Forums
It is my bible when installing an OS on my machines and also when I am fixing friends and family machines too.
Now if you go through it slowly you will find lots of tweaks and they are all really thoroughly done by the authour Brink a fellow who is in my mind brilliant and if you need to ask questions he is just the most obliging person around.
The other thing is that you may lose some of the "bling" such as transparency (you don't have to I find it unnecessary) and all the tweaks are reversible.
If you do get stuck just post back in that tutorial and you will get help. Another bonus using this tutorial is that it helps you find your way around your machine and Windows 7!
Just one tip I would say you start with is do this
Registry - Backup and Restore - Windows 7 Help Forums do this and it will save you a lot of grief if you are ever doing things in the registry and even if you don't it is a good back up to have if your system ever gets corrupted.
(pretyped to save time)
