Whelp...I really have no idea what i'm doing wrong 
I installed everything, and it crashes. So I took out just the rocket science add-on, and it starts up fine, with no crashes. I added it back in, thinking it just needed to install IC2 first. Still crashed. Here's the crash log:
Display Spoiler
Mods loaded: 3
ModLoader 1.1
mod_MinecraftForge 1.3.3.12
mod_ModLoaderMp 1.1v4
Minecraft has crashed!
----------------------
Minecraft has stopped running because it encountered a problem.
If you wish to report this, please copy this entire text and email it to support@mojang.com.
Please include a description of what you did when the error occured.
--- BEGIN ERROR REPORT d3f4451a --------
Generated 16/04/12 2:47 PM
Minecraft: Minecraft 1.1
OS: Windows 7 (amd64) version 6.1
Java: 1.7.0_03, Oracle Corporation
VM: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
LWJGL: 2.4.2
OpenGL: GeForce 9400 GT/PCIe/SSE2 version 3.3.0, NVIDIA Corporation
java.lang.NoClassDefFoundError: ic2/platform/ItemCommon
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.Class.getDeclaredFields0(Native Method)
at java.lang.Class.privateGetDeclaredFields(Unknown Source)
at java.lang.Class.getDeclaredFields(Unknown Source)
at ModLoader.setupProperties(ModLoader.java:1728)
at ModLoader.addMod(ModLoader.java:268)
at ModLoader.readFromModFolder(ModLoader.java:1305)
at ModLoader.init(ModLoader.java:820)
at ModLoader.AddAllRenderers(ModLoader.java:189)
at afq.(afq.java:80)
at afq.(afq.java:9)
at net.minecraft.client.Minecraft.a(SourceFile:265)
at net.minecraft.client.Minecraft.run(SourceFile:648)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: ic2.platform.ItemCommon
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 25 more
--- END ERROR REPORT d017b8fc ----------
Anyone know what the problem might be? I've seen a lot of other people getting similar crash reports.
Thanks,
Greenman</init>