Headset

Do I need a new headset? The old one I took off the frame is I guess the original one, and came out pretty easily (the pressed bits that is - fork crown race still in situ!)

I was thinking of getting either this...
http://wiggle.co.uk/ProductDetail.aspx?Cat=cycle&ProdID=4000000835&N=Shimano%20STX%20Threaded%20Headset

or this...
http://cgi.ebay.co.uk/Shimano-105-Headset-1-inch-BRAND-NEW-be-quick_W0QQitemZ110165280670QQihZ001QQcategoryZ22679QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Can I put a 105 onto a MTB frame? It's 1" which I need, or do I have to go with the STX version, which I have experience of?
These look an improvement on the bearing retainer style headset that came off it?

Thoughts?

Anyone? Or am I just been dumb, and any 1" threaded headset will do?

i've got a nice chrome tange levin ( campy record copy ) headset 1" threaded if you do fee like replacing current

My concern is, the one that was in, pretty much fell out... and as it should be a resistance fit, thought it should be replaced!

Got a tight budget, so just wanted to know if both headsets would be ok? Would the Levin headset fit? Any pics?

http://www.parktool.com/repair/readhowto.asp?id=127
There are actually two types of 1" headset.. yay! :)

99% sure mine is "Modern European" Standard. The one in the pics is what I currently have (cage bearings cups etc) 22.2mm quill stem etc.
As the cups pretty much fell out I though a new cartridge style unit might be the best replacement. So can I use the 105 unit, the STX unit, or both?
Sorry, I know a lot of bike stuff, but stuff like this I am always unsure of? Cheers