Advice from the Access conversion world:
Make a copy of your database before you do anything. Trust me on this!
In Access you can use the upsizing wizard to convert the tables to SQL server. Then you link the tables in Access and they will work just like Access tables if you wish. When you link the tables will come in with the owners name attached (usually dbo if you use the wizard)so Profiles becomes dbo_Profiles. Just go in and rename them and all your forms, queries, etc. will work. All your tables will need a unique field of some kind or you won't be able to update them through Access. Also, the datatypes will be different and you many need to check that the upsizing wizard really picked the type you need. Read about data types in Books on line.
Now comes the hard part. You will not gain the speed advantage unless you convert your queries to stored procedures. Since many Access programmers don't directly write SQL (Allowing the query by design to do it for them), this may be a whole new world for you. Get a good book on Stored procedure programming if it is. Also, even if you have written Access SQL statements, you need to know that Access SQL and T-SQL are different flavors of SQL and have some differences. So just copying the Access SQL code into a stored procedure won't do it in many cases. A few of the places where converting is a pain are cross tab queries and queries where you directly refernce an object on the form. These are much more complicated in SQL and you wll have to learn new methodologies to do them. On the other hand, T-SQL is much more powerful and you can actually perform multiple actions in one procedure. My advice on converting queries is to go through your site once you have linked the tables and see what is running slowly. Convert these queries first. (Once you have some concrete examples of what you want to change, we can help you find the syntax, but really read up about stored procedures first or the advice won't make any sense.)
Now you also have some problems, you may not have had with Access like database admin, backup, security (many Access databases do not use any security), triggers, data transforamtion services. Lots of new things to learn. Make sure you set up backups because your transaction logs (another new thing you didn't have in Access) will grow tremendously large and eat all your hard drive if you don't. Another fun issue is that any changes you make to the database structure in SQL server, require you to relink the tables in Access.
Oh yeah, one other thing, when you set up your connection string to SQL Server, do not use the sa password to connect to the database. Either let everyone use their windows username and password or create a special user for the connection (or an application role). ANd do not under anycircumstances leave the sa login with no password (unless you want to get hacked into!) sa is the system admin userid and has the rights to do anything to the database - do not let anyone but the dba have this password!
Hope this helps. You will need more info as you go along, but this should get you started on what to look at.
Judy