DOS Batch - File extenstion removal in loop

I'm Really new to creating these batch files. I think this is the second one I've made.

I need to find a way to remove the file extenstion from the %%I variable or set it to a normal %i% type variable so that the zip file does not say *.txt.zip

@Echo off
cd\
cd\test
dir *.txt /B>tmp
FOR /F %I% IN (tmp) DO (
Echo %%I
7za a %%I.zip %%I.txt
pause
del %%I.txt
)
del tmp
pause
exit


Also if it helps I am creating this batch on Windows XP but I need to run it on a Windows 98 machine.

Thank you for any help!