To IS or not to IS: Image Stabilization

[poker]

I recently purchased a Canon 70-200 f/2.8 L USM non-IS. After using it at the beach and bonatical garden, I'm starting think I lack the ability to handle a large lens with the 2x TC. My photos when magnified in PS are somehwat soft. I've used the lens with a monopod and tripod. Tripod usage is fine but my tripod is very heavy to bring around. I don't know if I'm using the monopod efficiently.

Should I bite the bullet and get the IS version? The price difference is $600 if you didn't know already.

I want to believe there are techniques out there that will help use a large lens efficiently. People were using long lenses way before IS came out.

Some will ask, well what are you shooting? Let's just say almost everything. I haven't decided on a niche. I will be using it for events and wildlife. I haven't done sports yet but will shortly.

Please share your thoughts and suggestions in using heavy long focal length lenses with or without IS (VR is the Nikon version?). It doesn't matter what type of photography you shoot. I will probably try it out soon anyway, so please comment.

Thanks in advance!