need a bit advice on Inspire T7900 and X-Fi XtremeMusic

I think for games, if you have the space to properly space the speakers with stands or wall mounts, it can make for a very fun experience.

For DVD movies the small speakers probably would not be very satisfying, as 75% of all the sonic information comes out of the center channel, which demands very good dialogue reproduction. Small speakers like the Inspires are going to have some trouble here.

Also DVDs are not amplified by +12db like WAVE sources are, so you need a lot more amplification to normalize the volume to what you usually listen to mp3s at (12db is requires almost 20 times the amplification...so movies will be somewhat quiet unless you have efficient speakers/powerful amplification. Small speakers are notoriously inefficient and bleed power).

For music, I think its a mixed bag. If you like to mirror your stereo music in all channels, you could get a larger soundstage as you normally would with larger stereo speakers. However the problem arises in that 6 speakers in stereox3 playing the same information at different sources will create holes in the frequency response from destructive interferrence. Getting better/bigger speakers for stereo performance would help here (playing music as it was recorded, with 2-channels), and I believe the Gigaworks G500 do fit that bill.

Anyway, getting a really satisfactory system usually includes both going to a higher price category and building a component system by picking and chosing parts (generally bookshelves, amp). By taking the commercial pre-built route you have to weigh your trade-offs: More speakers? Or better speakers?