OS X Server ok for 0S9/X + Windows clients?

Our office is thinking of getting in some PCs to start infiltrating our Mac desktops. The reason for this is that our CAD programme is no longer produced for Macintosh (Microstation). I am busy looking into filesharing issues. We presently have an Ethershare 100-user license running on Linux, and this works very well. Helios are bringing out their AFP 3 compliant server out in the next month or so, and they have a product called PCShare which can provide good PC sharing capabilities from the same share. The downside is that this all costs a lot of money. We also use netatalk on Linux, and it works great for both OSX and OS9 so long as the OSX clients dont try and use long file names. Netatalk doesn't share locks with SAMBA, which we also use, which makes this solution a non-starter until the Netatalk team make their proposals for shared file-locking and AFP 3 support a reality. I believe the latest Windows server products don't offer AFP 3.0 support either. Is this really an issue? Are there any file locking issues? So I'm now looking at OSX Server(!). Are there any problems with Mac and PC users using the same fileshare? Surely there are locking issues if OSX is using SAMBA -- or is Netatalk sensitive to SAMBA's file locks? Thanks very much for any advice. Rory