I have got illustrator and indesign available on subscription, but if i can hold of till i arrive back at home i have got full cs5 - if the method mentioned above via photoshop is going to be the easiest solution?
For print 300dpi is generally considered the minimum, but you can get away with less, like posters which are generally viewed at a bit of a distance look OK down to about 225, things definitely start looking crap at 200 though. I would use Photoshop too.
I've tested this to extremes 'cause I really am that dull. The same 300mm x 300mm print. Two versions of the file a 300ppi tif and a 200ppi tif (down sampled from the 300ppi) great quality start file. (Note: the res is at final output size.) Printed side by side on the same machine (HP5500) at the same time (so same in all respects other than ppi of original file.) I couldn't see a difference. Under a lens I still couldn't see a difference. Over a month of asking people which they thought was which I got close enough to a 50/50 response that it was clear that no one could see a difference!
Far from looking crap at 200ppi. With wide format digital print you never need to go above 200ppi at final output size.
As a quick tangent.... Folk often say dpi when they mean ppi. Worth a thought because they don't mean the same thing and they're not interchangeable. Files contain pixels, thought of as square, each of which is normally one of 16.7million colours. Printers fire dots, which are thought of as round, and tend to be one of four colours. They are nothing to do with each other, and don't relate to each other in any way at all.
That's interesting. If you're asking for a digital file set to a resolution of 300dpi I'm afraid you mean ppi.
Have a close look at Photoshop or any of the Adobe suite and see if you can find somewhere that you can set DPI. You'll find that you can only set pixels per inch NOT dots. Image files don't have a dpi as they're not made of dots. So if you ask for an image file at 300dpi you're confused. You can of course print an image at an output resolution of 300dpi. Those two things have no relationship to each other at all.
When you get a client ask what resolution the printer is... you can be pretty sure confusion is paying a visit. A designer shouldn't care what res the printer is. Care what size the dot is, that makes sense, but the number of dots almost never matters at all!