Constant HDD activity

[Darxide]

This relates to the 'Media PC' in my sig. I know it's old and underpowered, but it does what I want. (Play HD video and old console emus).

I took the old 250Gb drive out and replaced it with a new Crucial V4 128Gb SSD. Because all my data is on the home server now, so the media PC really only needs an OS and a few apps, and 128 is more than enough, and faster to boot.
So I reinstalled Win7, and drivers etc.
And now it's practically unusable due to constant HDD activity. The LED is on solid, save for the odd few seconds.
I don't get what's causing it. It's a fresh install, and I haven't loaded any programs yet. It did a lot of windows updates, and that took forever. Even opening a browser window is a slow painful task.
Would a faulty SSD cause that? I doubt it's a bad SATA cable as I'm using the same one as before. All I did was take the drive out and put the SSD in it's place.

Any ideas?

[Scubar]

Have you disabled things like hibernation, system restore, drive indexing ?

these are all highly recommended when using an SSD. If its a new install its more than likely the indexing thats doing it.