Heh, well the good thing is that you're certainly heading in the right direction!! Not sure how much speed benefit you'll notice, but you will certainly improve the efficiency of things.
I would do things in this kind of order:
- Lock your door so the users can't get to you to gripe about locking them down (haha)
- Make sure you have Active Directory containers configured how you want them. This should't be too bad with only 50 PC's.
- Create domain user accounts for your users in AD
- Create home network shares if you want to use them
- Configure the domain's Group Policies in AD
- Write login scripts if you want to use them
Configure your PC's to use your DC as the dns server if they're not already (or whatever dns server holds your AD SRV records). You might consider setting up DHCP at this point if you don't already have it in place. NOTE based on comments: DO USE DHCP! The prior wording was supposed to say that, but admittedly was not clear. Set up DHCP and configure your clients to use it.
- Back up your users' profiles on their PC's. They will get new user profiles with their domain accounts.
- Join your PC's to the domain
Some of that can be switched around a little but basically it's
- Set up your domain and group policies
- Set up your user resources
- Migrate the PC's
Do this with a handful of PC's in a a lab before you do this in production until you are comfortable with the process. You'll also benefit from a workstation naming standard when joining your PC's to the domain (from a sanity perspective).
Here's the site to start learning about group policy.