Do you think it is good or bad to download every update for your computer and internet applications?

Personally, I do not install any updates on operating systems. I feel like the amount of bloat that they put on your system is just way too much. For applications if they have an automatic update I'll let it install (Firefox for example). For hardware updates, its good to check out the updates (HP.com for your HP laptop for example). Sometimes these upgrades to your video card or wireless card will really go a long way. But for Operating System updates I have never installed one update, ever, and I'm still doing fine.

Every one of them? Bad.
There are parts to every operating system/apps that are designed to monitor, report, and just kinda weigh down your stuff. Many even try to control what you are using your products for.

Base Example: Halo 2, you used to be able to cheat and slash across a screen and do a lot more interesting things, one of its first updates was to prohibit this.

My advice is to use the custom function on most upgrade panels.