Another thing I've noticed has to do with WiFi on the Inspiron 9400.

It has an internal PCIe slot for a wifi card, and originally shipped with a Dell (Broadcom) A/B/G card installed. Those now work fine with Linux, but I replaced it anyway with a new Intel ipw3945 A/B/G card.

The Intel card out-performs (range) the Dell/Broadcom card by a fair bit.
Well worth the $40.

Cheers