What should I do first?

Hey guys i've just buited my PC and also added a 1TB HDD but i don't know if i should install my Windows 7 on HDD or just save for a SSD because I just used all my money for my PC and from what i know the OS is sugested to be on a SSD 


Just put it on the HDD. You can move it to the SSD later.

Just download it on your HDD, if you choose to buy an SSD in the future you can reinstall Windows fairly easily, it usually takes me a couple hours max to fully install and customise windows.

EDIT: Not sure why I typed download, disregard that.

I would save up for an SSD, configuring everything (for me atleast) was a pain. Mostly because I have a crapload of programs I run at all times

Make sure that if you do decide to install your OS on the SSD later, that you unplug the HDD before doing so. If you don't, it could cause problems with windows.