For prolly at least 75%, maybe more like 90% of users these speakers are great.
Some people might tell you the sound quality sucks... but unless you are used to 200-500 dollar sound systems you wont care. Hell I used to have Harmon Kardon like 10W speakers about 3 years and they worked fine for most of my uses (including games/music)
These are nice speakers, and for the price they are VERY nice.
If you had more money burning a hole in your pocket however you might want to check out Logitech z-560s, tremendous increase in power (not that the 640s arent really powerful enough), for about 150 dollars