I have a 120GB SSD and a 1TB HDD and I would like to have my steam library and steam on my HDD cause I don't have the space on my SSD but how do I launch Steam or any Steam games when I boot from my SSD and my desktop is from my SSD.
Better way to do it is to leave steam on your ssd and use this to move your games. http://www.stefanjones.ca/steam/ this is what i'm using, you simply transfer your games from your ssd to your hdd then back when you want to play a game.
Ah ... that's a nifty little tool there. You don't actually need to keep moving games around - it just makes sense to have the ones that you use most frequently on your SSD (or more accurately the ones that get the biggest boost from being on an SSD). The others should still run from the HDD if the tool is doing what I think.
I'd been doing this manually by moving folders from the Steamapps folder on my SSD to folders on my HDD then using the MKLINK command to make junctions. This is easy enough but still a little bit of a pain making sure the paths are exactly right. Basically the junction creates a "logical" pointer to multiple physical locations.