I've recently decided to upgrade my rig. I've been using a fender solid state combo which I had gotten years ago, but now I really want to upgrade to an amp that can handle Prog Metal stuff like Dream Theater/Opeth. My budget, however, cannot exceed $1500.

Any suggestions would be greatly appreciated.

Also does anybody have suggestions on effects for this style of music?
are you looking for guitar/amp/effects?

Guitar I would recommend anything with a H/H pick up set up. Amps, well any tube combo in the 5-50 Watt range depending on application. Effects, get a Chorus, Delay and/or Reverb, and anything else you anticipate you would use.

There are a lot of recommendations for Guitar and Amp, but I would say you need to go out and try some different brands to see what fits your budget and style - but I would highly recommend looking at tube combo's for sure

hope that helps

Epi Les Paul Std w/Duncans
Cry Baby From Hell
Marshall JH-1
EHX Metal Muff
MXR EVH Phase 90
Carl Martin Classic Chorus
EHX #1 Echo
Ibanez LU-20
Dunlop DCB-10
Crate V50112
Tascam US144

Really basic, I'm rocking a Fender Strat outfitted with a Super Distortion in the bridge and a YJM in the neck. No pedals, and the amp is a Fender Solid state Twin reverb
Well I think I'd go down the nice combo route and maybe some effects with the change. You should be in Mesa Combo territory with your budget. Id say look out for 2ch Dual Rectos or Mark combos, likely a Mark3 with your budget, im not sure if Mark4 will be in your price range unless you get lucky. The only thing i can advise if looking at mesa is try to avoid parallel loops as they are a right bugger to get sounding good.
ESP M-1 - Dimarzio Super3
Ibanez RG3270 ToneZone/Blue Velvet/Paf Pro
Ibanez RG1527
Mercer Blackmachine Replica

Diezel Herbert
Diezel Einstein Combo
TC GMajor

Gain Wh0re and Diezel Mafioso