Hi all,
Am new to this entire home projector thing and am just learning about it. My question is,
if the projector states that the aspect ratio is widescreen (15:9) does that mean I have to get a
(15':9) projection screen. Can I still use it with a 4:3 screen? Will it not work properly or would the picture on a 4:3 be messed up? Thanks ahead for any responses.

Yes, you can view 15:9 on a 4:3 screen. You'll just have the normal black letterbox bars at the top and bottom of the screen. This can be compared to watching a widescreen movie on a regular 4:3 TV or computer monitor.

If you're talking about the eVo projector, you can use a 15:9 screen and when viewing 4:3 movies/programs, you will then see the screen pillar boxing - black bars on the left and right of the screen with no black bars at the top and bottom.

Letterbox:
http://en.wikipedia.org/wiki/Letterbox

Pillar box:
http://en.wikipedia.org/wiki/Pillar_box_%28film%29