You could use the hdd but the OS would not accept the motherboard as being appropriate, the chipsets would be different. It's much like putting a hard drive from an Asus rig into a Gigabyte PC, the chipsets are different and you'd get BSoD's. There is no way around it. You will just have to wait for the SSD or just go but a regular hdd, 500gb is only about $50, some 1TB hdd's are only about $90.
Even when you get your new SSD, you will need to acquire an operating system CD disk. If you eventually do get a rig al set up, you could use an external hdd enclosure and then transfer your files from the old laptop hdd to your new PC, not programs only your files. Some games can be copied from the Progam Files folder without need for re-install but only those older ones, usually.