You can only choose resolutions with vertical frequncy of 15khz - it will not display such things as dblpal (30khz) of euro72, and in trying you could damage (or even blow up) your monitor. The non-interlaced ones have fewer horizontal lines, but don't flash like the interlaced ones do. I'd use that for most things, but switch to interlaced when you need a high res screen (eg photo editing).
Alternatively get an amiga-vga adapter (few quid on ebay) and use a dblpal screenmode on a PC monitor capable of displaying 30khz.
For monitor info try here
www.monitorworld.com/You can mess about with utilities form aminet such as MONspecsMUI, which allow you to adjust sync rates, frequencies and blanking values, but be very careful as this can destroy your monitor. READ THE INSTRUCTIONS BEFORE USE, and if in doubt, DON'T MESS WITH IT.
www.Aminet.net Your new best friend for amiga resources.

If you haven't got your amiga on the net you may want to format a couple of floppies on your PC (to 720k capacity), set up CrossDOS (by dragging PC0 from your storage/dosdrivers to devs/dosdrivers drawers) and manually transfer files on floppy between amiga & pc.
Good luck