#1
im looking at theses amps currently and i want to upgrade, currently i have a little samick thats old and its kinda bad

http://www.thomann.de/ie/orange_crush_12...

http://www.thomann.de/ie/fender_mustang_...

or a marshall G80RCD

im open to suggestions i have also thought of a line 6 pod but im not sure, i like to play greenday, ac/dc etc i might also be getting a strat affinity and might try stratty kind of music, im still kind of a beginner
#2
In that price range go used. You won't get anything good for that price new.

I would recommend a Peavey Vypyr. They run pretty cheap used and are very good amps for practice.

Also, you should have posted this on the Guitar Gear section
#3
Go for the Roland Micro Cube Gx ... only 2 watts but damn its so loud... it sound really good... its a "smart" amp :P .. you can easily jam with a drummer (thats to show you the volume) It has all the effects and a memory (to save your settings)
#4
Biggest Vypyr you can afford. Or maybe the Vox VT series for lower gain models. Also based on the two bands you listed I'd be looking at a different guitar, the Affinity's are hit and miss and not really suited to that kinda music - I'd suggest something like an Epiphone G-400.

Used gear is your friend, so long as you check it out first.
#5
Agree with the Vypyr, but that's because I don't have experience with the Roland, so I can't comment.
And the affinity will be fine. As long as it has a humbucker, it will play greenday, ac/dc, pretty much anything just fine. Worry more about how the guitar feels and plays than whether it suits your particular style of music.
Harmony: Stratocaster
Alvarez: F-200
Schecter: Omen 6
Fender: BXR-60
Dean: Metalman Z Bass (Betty)
Egnator: Tweaker 15
Pearl: Maximum
ESP/LTD: EXP-300
Custom: Harley Quinn Bass
Custom: TK-421 Explorer
A steadily growing supply of pedals