Welcome to the forum, puppethead.

Depending on your needs and long-term plans, either approach can work well. Separates can help with long-term upgrading because a good power amp can last a long time (as the five-year warranty on Outlaw's amps suggests), allowing you to only have to replace the processor portion of the system if you want to move up to HD-DVD and Blu-ray in a few years or want to upgrade for other new features or sonic benefits. A receiver gives you everything in a single box, saving you some extra wiring, but also requires you to replace the amps and the processing if you decide to upgrade in a few years.

Outlaw gear is being used with a wide array of speakers: British brands like B&W, Canadian brands like Paradigm and Axiom, a number of different Polks, Klipsch, Onix Rocket, Aperion, Boston Acoustics, and a bunch more that I'm probably forgetting. The Outlaw equipment has been pretty consistant in its neutrality (not particularly "bright" or "warm"), so if you get speakers that suit your personal tastes the Outlaw equipment shouldn't influence that sound much.

Outlaw works hard to make solid, reliable gear that will last and that will sound good along the way. NAD and Rotel are two of the separates brands closest to Outlaw in price, and Outlaw consistantly matches them (many people actually prefer Outlaw, although there is some personal preference involved). Similarly, HK and Denon in the same price range may offer a few extra bells and whistles (they benefit from the larger R&D budgets of large corporations), but for sonics and reliability the Outlaw is definitely competitive - and Outlaw's customer service is going to be faster and friendlier than any of the brands above.

If you are looking for a music system now that can expand to do home theater, I'd certainly recommend taking a look at the 990 and an Outlaw amp of some sort. You could do a pair of M2200's now and add a 7500 later to provide amplification for the rest of the surrounds, or just get one of the multichannel amps and add speakers down the road as you expand. I am not familiar with the Jamo's to know what amp might be the best fit (whether there's a need for the 200W offered by the M2200, 7500, and 7700 or whether the 7125 would work just as well), but others around here may know. (EDIT: The Jamo D450's are a 4ohm load that are 89dB efficient - at 4 ohms, the 7125 would provide 190W per channel and the 2200, 7500, or 7700 would provide 300W per channel. Any one of those would probably be comfortable keeping the D450's fed.)