Components are the key to MechCommander, the mech's are merely casings. Without a successful selection of weapons and electronics they are nothing! Components are either sensor based such as the sensors and ECM or weapon based. Weapons are split into 3 ranges, short, medium or long.  Clan weapon details are listed here too. Generally clan systems are much better all round (in the campaigns), wherever you can use clan weapons - they have no drawbacks! (except their rarity). In the multiplayer missions you pay a lot extra for clan weapons. 

Clan weapons have a little triangle as their logo instead of a circle which is visible in their logo. They are also named with a C at the front C/<name>

The top one is IS, the bottom one is Clan

Soon I will also have full (large) pictures of the weapons as you see them when you but them, however for now I haven't got the time!

Weapons

Short range:

Pulse Laser
SRM Pack
Laser
Streak SRM Pack
Heavy Flamer
Heavy AC
Heavy Ultra AC

Medium range 

Lrg PS Laser
Large Laser
Autocannon
Ultra AC 
ER-Laser 
PPC  

Long Range 

LRM Rack
Light AC  
Lt Ultra AC 
Lrg ER Laser
ER-PPC
Gause Rifle

"Sensors" 

Sensors - Basic 
Sensor - Intermed  
Sensor - Advanced
Beagle Probe
Guardian ECM  

Links:

Strike Base Alpha - (http://web.utk.edu/~tone/mcsba/) - Contains details of Mech Commander mech's & components.