I need help upgrading my system

Sorry but I'm just not familiar with the Klipsch sound nor could I find any data on the La Scala's at the Klipsch website. I would say that large floor standers for a room 10' x 10' x 8' high could be overpowering. I good pair of bookshelf speakers such as the B&W 685's, older DM601 S3's or DM602 S3's with an NAD or Marantz for example 2 channel integrated amp or receiver will (IMO) blow you away. Does your room have carpeting? A used Denon 2 channel receiver could be a good choice too. I wouldn't go any lower than say 50 watts RMS per channel. I hear great things about the Outlaw Retroreceiver at 100 watts/channel RMS. Check it out at their website. I came close to buying this but went multi-channel surround sound for both home theater and music.

Yes, my room does have carpeting. Also, will any of these speakers sound any better than others with metal and gaming from my pc? Also, say I went with the denon amp and the b&w speakers, should I continue to use the sonic maximizer?

Yeah, the deal is that the Cheap Denon's with the new Audyssey EQ is going to be LIGHT YEARS better than anything else you could EQ your system with! So, even if you go 2 channel, you'll still be WAY ahead of the game, sound-wise. Infact, you'll be even better off, as you'll be needing less processing power - because you're using only 2 speakers, not multiples, which need EQ'ing.
For you? I'd be looking at high efficiency, possibly horn driver or multiple mid/bass driver speaker designs! You need something that can be driven by lower powered on a budget, if you're not doing separates.
Again, with something like a $450 Denon (retail - much less on net), you should be looking at Klipsch's, Dappolito's, and dual mid/bass designs, which do better at dynamics. That's for bookshelves, and preferably floorstanders, also. For your room, with the Audyssey, you could EQ out floorstandars. But rock will be better running speakers as "small", and letting a powered sub handle the bass! You'll then be bi-amping your system, while getting an active sub into the mix. In fact, I'd be looking at bookshelves, if it where me, and doing a sub, yes. Better flexibility for best sound, all around, I think. However, with an efficient enough speaker, you could get away with EQing it out, and proper setup, for great reasults, if careful. Some speakers out there offer active woofers, so look around.
My first thought for you, for a budget, with superb sonics for you, is the Cheapest Denon with Audyssey, MultEQ. Then look for either some horn speakers, like Klipsch RB-25's, or some Dappolito designs, like Paradigm, NHT, or PSB L/C/R's used on the net. These will all be dynamic for rock, and help reinforce transient response, while being more room acoustic friendly, wiht added efficiency.
Another very strong option for you to look at, in a more high-end, but affordable speaker option, is to look at the Triangle Titus and Comet speakers! These offer a simple crossover, which makes the speaker respond more like an active speaker! This improve dynamics greatly, as does the horn like tweeter they use. These are WELL worth a try for you!
Sub? I'd look at some 10" you find a good deal on, which has a good bunch of reviews. (I found a killer little 8" sub for $20 on craigslist.com). So look around - same for speakers.
You can then scout around for speaker wire cheap, and IC's, tweaks, etc.
Hope this helps.

Thanks for the help, Flrnlamb. I'm gonna go with the cheapest denon. Do I need one with Audyssey? And if so, which one is the cheapest with it?

What does Dappolito mean?

Any other recomendations with the fact that I'll be listening to metal and gaming w/ them in mind? And also price is a big factor too.

Thanks for the help so far everyone!

~max

Also, I'd rather not have a sub, so what speakers would be efficient, be good with metal and games, have active bass, and be fairly cheap (used)?