Informal Invitations (Help Please)

My fiance and I are having a casual ceremony w/ a pig roast to follow on 6/5/04. I am making the invitations myself. And to suggest that this will not be a formal occasion, I went with printed stationary instead of formal invitations. Does anyone have any advise on how I should word them or know where I can look for examples...etc.? Also, we are providing all beer, wine, and soda but are not having mixed drinks due to the expence. Should I add something about that so those that prefer mixed drinks are aware it will not be provided by us? By all means if they`d like to bring, they may.. But I feel uncomfortable putting that in the invites. If anyone has any advise, please let me know.

Thanks