There are many software options for creating your poster.
MicroSoft PowerPoint is a relatively easy-to-use tool for
creating posters - see instructions.
One benefit of PowerPoint is that many people already know how to use it.
Adobe Illustrator and InDesign have more features and can provide
very professional results - especially for posters including lots of
high-resolution imanges - but are more complex and expensive.
MicroSoft Excel can create graphics and export them for PowerPoint -
but you'll need to clean them up.
DeltaGraph is also a nice tool, but keep your graphs clean.
no-cost alternatives to MS Office. Impress is the PowerPoint alternative,
and Draw is a vector graphics software package.
See the OpenOffice web site
or their documentation section
for further information.
Adobe Photoshop is great for manipulating images, but is also complex and expensive.
All software packages will allow you to
print a scaled-down version
of your poster on a standard (for the US) 8.5 x 11 sheet of paper.
This is an excellent way to improve draft posters - and circulate
them for editing - because if you can read the reduced version comfortably
your fonts are large enough to be seen from 1-2 meters away
at full scale. Plus you have an instant handout!!