I have a 2 channel set up. What is the best way

I have a REGA Mira 2000 integrated amp and what to get into surround sound. I am running B&W 602 as my main speakers. I have a center channel speaker and surrounds. Could I purchase a A/V received and hook it up with my integrated amp? In other words, would it work if my integrated amp ran the main speakers and a A/V reciever ran the center/surround speakers? I want to leave my main speakers hooked up to my integrated amp. What are some other possibilities?
I would buy a 3-channel amp for the center & rear speakers.
Then all you would need is a dvd player with d/d decoder built in it.
The approach you are considering will work, but the hook-up process may be a little complex. Another approach, which many people with 2-channel systems have used to get into HT, is to buy an outboard surround processor and a 3-channel power amp (for the center and surround speakers).

I have helped several people install the Technics SH-AC500D Surround Processor, which provides Dolby Digital 5.1, DTS, and ProLogic decoding. The unit also provides a pass-through circuit that lets you operate your 2-channel system without running the signal through the digital circuits. This model can be purchased discounted for under $300. My son has one of these units in his HT setup, and I've been impressed with its performance for such a low price.

If you decide to get an outboard processor, you will need an external 3-channel power amp. There are a number of moderately priced amps, such as the ones made by Adcom (used 5503's sell on A-gon for around $600-650) and Rotel, and if you really need to save some money, the amps made by AudioSource have gotten pretty good writeups by non-highend audio mags.
To work as I've suggested, your integrated amp would need both "pre-amp out" and "pre-amp in" jacks on the back panel. The signal from the "pre-amp out" on your integrated amp would have to be routed through the Technics surround processor, and then back from the processor to the "pre-amp in" jack on the integrated amp. Then, the integrated amp would be used to drive your front speakers. The surround processor has additional outputs on the back that go to the 3-channel amp that will drive the center and surround speakers.

While the surround processor is engaged in the circuit, it will decode the 5.1 signal, feeding the decoded signal to all 5 speakers, plus a subwoofer (if you have one). The surround processor also has an output on the back panel to drive a subwoofer, but if you have no subwoofer, you simply program the processor for "no sub", and it will feed the full-range signal to the main front speakers.
Thanks for the tips. How do you feel about doing this with a A/V receiver. My brother has a A/V NAD receiverto sell to me for cheap. My integrated amp has the in/outs that you said I need to have.
An HT receiver is a good way to do this. You don't need a three chanel amp this way. Make sure the receiver also has inputs and outputs for the main channels.
With the receiver, if it has pre-outs for the main speakers, it's a bit different. You would keep your analog/music sources (CD, LP) connected to your integrated, and connect the video sources (DVD, SAT, VCR) thru the receiver. Run the L/R mains pre-outs from the receiver to an auxiliary input on the Rega. When you calibrate your HT surround levels, mark/memorize the volume setting on the Rega, and always return it to that position when listening/viewing material thru the receiver. You can do the same thing with a surround processor and external amp.
There are several integrateds available that offer theatre throughput. Most are, at worst, a performance peer to the Mira. On the cheap, a Classe CAP100 can solve your stereo listening and when combined with an older processor and a three channel amp will give you very nice results. My own system is a CAP150 with Marantz AV550 processor and Adcom 2535 three channel amp. Less than cutting edge for movies ... but more than sufficient to enjoy movies in your living room.
To Stbhorn, just to let you know about the receiver-preamp combo (in your case receiver-integrated) thing. On the cheap I did that for a year while saving up for a power amp 5 channel. Probably the only guy in the USA that ran an Audible Illusions 3 tube preamp into a Pioneer av receiver. You would be greatly surprised how good that receiver sounded when it was released from preamp duties and only had to pass power.
upgrade your 2 channel setup (spend the money there) and stay away from home theatre nonsense

the fellow recommending the Technics processor and a three channel amp makes sense. My only addition to that is that the Technics was a relatively inexpensive product. I acquired a used Sony ES dolby digital processor; it also has the analogue pass through. But, I use a little passive rca interconnect switch box to connect my stereo preamp (McIntosh C22) and my processor. This works great; the main outs from the sony processor can feed the audio note tube amp or the main outs from the mcintosh feed it...

the switch box was made by an outfit called db audio