Overall, your system is more than capable of glitch-free playback. The HDD is on the slower side, being 5400 RPM, however it shouldn't be the culprit. On the other hand, the GPU is a low end model, and if you intend on doing a lot of audio playback/recording, I would recommend you disabling desktop composition entirely.
You should never update drivers through Windows Update, always from the hardware manufacturer instead. Unfortunately, Sony is one of the few brands that still do shameful Device ID swapping and sometimes adding hardware adapters to make it harder for replacing hardware, which in that case you should first update to the latest drivers available from Sony, then individually updating drivers from the hardware manufacturer itself.
Lowering color depth does indicate that the issue might be related to the GPU. The easiest way to check whether the GPU might be faulty (despite being low end, it should handle full Aero with little degradation) is to go to system properties, Advanced tab, Performance Settings, then selecting the best performance adjustment. Restart your computer and test whether you still suffer from those issues. This, with 32-bit color.
I had actually done this previously, but did not think of restarting my computer. Will try and let you know.