If you think it sounds good then I'm not going to convince you otherwise. Have fun with it, but with 5.1, you may want to consider a component set bot front and rear so you can better adjust the speaker imaging with the added mounting possabilities a seperate tweeter gives you
Also, you may want to look at a dedicated woofer for lower frequencies to put in the front, allowing you to cross the subwoofer at 60hz or lower, making it harder to locate audibly.
I would suggest something similar to this, the numbers are rough because obviously all speakers have different characteristics. If you truly want the best sound you can get you are going to have to look into equalizers pretty soon as well. With that many different size speakers playing at once, there is bound to be some unwanted noise.
1+2- 7" woofers (60ish to 800ish)
5.25" mids (800ish to 10Kish)
tweeter would cover the rest
4+5- 6.5" midbass (80ish to 10Kish)
tweeters cover the rest
3- 5.25" mids (80ish to 10Kish)
tweeters cover the rest
.1- a subwoofer to cover anything under 60Hz.
