It may take a while for you network discovery to find all of the computers in your environment. Not only does SMS have to find all of the nodes on your network, it also has to update the database.
If you are not "finding" all of your workstations, check your SMS Site Boundaries. This is where most people have a problem. (Although the problem is usually with SMS Site Assignment...not discovery.) Remember that Site Boundaries use the IP subnet MASKS of the client machines. If you think you may have a site boundary problem...or you don't understand how site boundaries work, just perform a search in this TEK-TIPS post. Believe me, you'll find a ton of POST from people with the same problem.
If you have multiple subnets in your environment, look at you SMS database. (The easiest way is to run an SMS defualt query...this way the IP addresses and subnets are displayed in a table format.) From the query you should be able to see if you are only discovering one subnet or if you are discovering various subnets. This will give you a good idea about where your problem exists. If you are only discovering the subnet that your server is on, you have a Network discovery issue.
Also, are you using DHCP? If you are using a DHCP server, click on the DHCP tab in the Network Discovery and enter the DHCP servers of your environment. (Make sure that the DHCP servers are part of your domain and the IP subnets of these servers are within your SMS Site boundaries.) After doing this, what a few hours. You should see all of the DHCP subnet ranges appear in your Network Discovery --> SUBNET dialog box. From here, you can enable select subnets for network discovery.
Anyway, I hope this helps....
(by the way, you must set up Remote Control in CLIENT AGENTS for SMS to install the Remote Control agent on your clients. Look for the ENABLE REMOTE TOOLS check box. On the client, you can look in the Control Panel for an ICON called SYSTEMS MANAGEMENT. After opening the SYSTEMS MANAGEMENT icon, click the COMPONENTS tab. This will display a list of installed SMS components. If you don't see Remote Tools, you have a problem with this client installation or your SMS Site isn't setup to install the Remote Tools agent. You should see at least 3 component here. Also, if you click on the SITES tab, you will see what site you are assigned to. If there is no site listed, you may have a problem with you boundaries.)