Sony Vegas if you can start a trial , otherwise you are stuck with Windows Movie Maker (lol).

trakAxPC is what i use...i can add pictures, music, facecams, and other stuff and it's pretty cheap for editing software..but..you can't slow down or speed up your videos with it..i was wanting to slow down some of my scares but i didn't see the option to..but other than that it's fairly nice..comes with a trial..i'd check it out

I use Adobe Premiere, personally. It's fantastic for everything I need, but a bit of a hassle to learn first-time.

I prefer Vegas Pro then Movie Studio. However that's just my personal preferrence. Or you can try Adobe After Effects. Well you don't have any money to buy those, I suggest stick with windows movie maker or you know find ways to download those good software trail or not

Sony vegas pro 11 is a good and neat editing software. It has many effects and a easy UI

If you're new to editing, Sony vegas would be the "best" (actually I hate it, but I have to use it anyway)
If you're looking for a reasonable software for cheap, Adobe premiere elements would be.
Also if you are a student you can get it for even cheaper. That's the best.
It's a bit harder than Sony vegas, but with youtube you can learn it pretty fast.
So my answer: Adobe premiere elements ( elements = 80% cheaper than elements but most of the original's features are not in it, but for a let's play, it should do just fine)
But most important: Before buying any of these, TRY IT THE TRIAL! To see if it does have all the features! Good luck!

Movie Maker -> Shit
Camtasia -> Decent, but not my fav
Vegas 10 -> For basic needs, a bit to hard to learn but its a great program
Premiere & After Effects -> For advanced users and are hard to master.

I just use Arcsoft Showbiz which I got for free with my Hauppage HD PVR Gaming Edition. It is really simple to use and it generally takes an hour to render and an hour to upload each video I pop up. It used to crash a lot but it doesn't anymore, so they must have patched it.

Basically all you need to do is capture your video in the capure tab and then pop the video in the Edit timeline along with the mic audio from Audacity and adjust the levels. So, so easy. It is rather basic though, but it is great for AMVs and Let's Plays. I just use Movie Maker for PC games. No real reason to pull my hair out with Vegas.

True dat, but actually it is not quite hard to master it, I mean for making let's play videos it is quite easy, at least if you
watch 1-2 tutorials you already know your way around it and unlike Vegas it won't shut down anytime
And for a let's play channel, after effects is hardly needed , I mean if you want to make an awesome intro, you might need
After effects, otherwise ,yea.

I use microsoft word. Its quite outdated now but gets the job done.

I use Adobe Premiere..
I hear Sony Vegas is good, it is cheaper.

LOOOL. Why not use Powerpoint, it's more advanced than MS word.:P

Kidding aside, Sony vegas is a good buy already. It's much easier to master I believe.