Just got a used Ipad 1 for free, it's got the 5.0 firmware or whatever that's called.
I understand that there's only a tethered JB method for this version...

Is there any way for me to install the previous version so I could have the untethered ones?

The device has nothing on it so I don't mind formatting it if that's the case.

 

As far as I no there is no way without SHSH blobs, however if you go http://www.limera1n.cc/ or just google it you should be able to jb ios 5 and then simply instal semi-tether. It's all good and sure even with a tethered jb - just don't turn it off and you wont have to re-jb it

Hope this helps.