Yeah well, onboard HD2500 graphics did not really do it for me. Even with the tricks mentioned before, i.e. to watch youtube using Chrome, all together, it was a little sluggish at the end.
So, I decided to put the Wimp in another case, in order to allow for a graphics card to be installed.
A Linux PC, based on an AMD E350 APU, which I used rarely, lived in a Thermaltake Element Q case. Although this PC actually needed the PCI-E slot for a network card, I decided to take it apart anyways.
Now, the HackWimp lives in an Element Q.
Looking you a graphics card, I found a passively cooled ASUS GeForce 8400. This card, which worked for Mountain Lion, refused to work with Mavericks... something I observed with other versions of OS-X.
Next trial: an original NVIDIA GeForce 8400, which always did a great job. And yes, it did! But this card has got very noisy active cooling.
Last try, a GeForce 8400 of a different brand, which I recently used for other purposes. Actively cooled, somewhat noisy, but not too bad. This card played plain dead!
The decision was to exchange the cooling setups of the two actively cooled cards.
Now I am running a genuine NVIDIA GeForce 8400 with 256MB RAM and tolerable active cooling.
This card allow for 1080p video to be displayed full-screen, which the HackWimp was not able to do before.
The choice of browser stopped playing a role, I am hence back to firefox...
Added bonus: the Wimp can now be hooked up via VGA, allowing for monitors w/o HDMI or DVI.