Feisty comes with a bunch of FX which are there by default. all you have to do is install the nvidia driver. Though i had beryl in both 6.06 and 6.10, i find that the default FX in feisty is more than enough ( plus beryl was beginning to get too superficial, and not to forget that most of beryl's fancy stuff wanted shaders , which my 4MX didnt have

)
With the default desktop FX , my pc is rock stable
but the Nvidia drivers killed the screensavers though, dunno why. whenever a screensaver kicked in pc would hang
PS , in 6.06/6.10, beryl made video playback a bit laggy. default FX are super smooth