Depends ifyou want something for music, gaming and watching movies
or something for music recording or mixing.
There is plenty of USB cards, some FireWire cards (rather for working with music) and PCMCIA cards.
PCMCIA ones are probably best laptop sound cards, e.g. Audigy 2ZS in PCMCIA version is identical with Audigy 2 ZS.
This would be good even for some basic mixing (audigy has ASIO drivers).
If it is for HTPC that is not used for gaming 24 bit Live would be a good card. For gaming look at USB Audigy NX
If you are more into music creation check m-audio. They have plenty of nice stuff in their mobile recording range. Same with motu.