i'm 22, about 6'1" / 6'2", about 12.5st, lean and toned

i'm after adding a few more effective muscle building exercises to my routine as i think i'm limiting my results at the minute by not doing enough. mainly not enough free weights. also thinking of switching around which nights i do which groups. currently do gym and cardio 5 nights a week, monday-friday with weekends off

currently:

mon, wed, fri - chest and back
tues, thurs - shoulders and arms (plus a small leg session)
i do my stomach the odd night aswell. just a few crunches and leg raises to keep it tight

current exercises: (excuse any novice names/explanations lol)

chest
bench press
pec deck machine
incline press machine

back
seated row machine
lateral pulldown machine (behind my neck, palms forward)
chin ups (wide grip, palms forward)
dumbell shrugs

shoulders
dumbell front raises (palms facing inwards)
dumbell side raises (palms facing the floor)
dumbell overhead raises (seated)

arms
dumbell bicep curls
dumbell tricep curls (lowering the weight behind my neck)

bit basic i know. but i have noticed alright results with it. although i'm sure i can do a lot better with the right routine

last night for shoulders/arms i did:

shoulders
dumbell front raises (palms facing the floor)
dumbell overhead raises
barbell miltary press (in front of my neck)
barbell upright rows

arms
barbell bicep curls
dumbell tricep curls

thinking of switching my routine to:

monday and thursday - chest and back
tuesday and friday - shoulders and arms
wednesday - legs, plus squats and deadlifts

gives more rest between muscle groups as i'm probably not allowing them sufficient time to repair at the min. i don't feel like i'm over training but chest/back three times a week is probably too much

what do you think?
what other exercises do you think i should be doing?

cheers, chris