What are 2.1 speakers?

I have a cheap laptop (Sony VGN NR430E), and have recently started listening to all of my music on it through itunes. My speakers are some old Altec ACS5's with a powered sub. I would like to upgrade speakers, and my laptop only has a headphone jack. What are 2.1 speakers? Are they for my laptop or do I need lower-end speakers? Do you replace the soundcard for better quality sound?

2.1 = 2 speakers + sub woofer/bass

5.1 = 5 speakers + sub woofer/bass

7.1 = 7 speakers + sub woofer/bass

In order to get the best surround sound with Dolby, you need at least 5.1 speaker system or 7.1 speaker system.

For example, with 5.1 speaker system, 2 speakers could be put at the back of the room and 2 speakers at the front of PC and 1 more speaker in the front, center/middle so this would give you surround sound effects and it is very good for gaming like it would make you hear your game's enemy characters' footsteps sound from your back if the enemies are approaching from your back which would make gaming more realistic and giving you the realistic real-world experience from the games.

True