I don't think it will be much of an issue. I have several sites with hundreds or thousands of posts.
Just to clarify though, you'll likely have fewer issues if you use WordPress "Posts" rather than "Pages."
Maybe you know this, it's in the codex, but just in case... Posts and Pages are different in WordPress. Posts will show up in the RSS feed, you can assign categories and tags to them. Pages are meant for your contact page, about page, etc. This is generally how WordPress is designed to be used.
I wrote briefly about this here but it's in the context of creating artists portfolios.
There's a video (recorded a while ago) by someone here. The key thing I would add to the video is that posts show up in reverse chronological generally, but the way you display content can be changed however you like.
And here's an especially good article about it by Lorelle