This should be in the games and graphics section as we got game experts here.

It is generally not wise to use a bunch of pictureboxes for games, let alone timers. There are graphical functions built in to vb.net, but if you want better graphics, you can use APIs such as BitBlt, StretchBlt, and TransparentBlt, all of which allow transparency which remove the background from an image, or if you wanna take advantage of the video hardware for either 2D / 3D theres DirectX and XNA.

You are also gonna need a gameloop locked at 60 frames per second. Im gonna be home shortly from work so Ill copy and paste code showing you how. And if you want real falling physics, Ill show you around that time as well.