SQL server will not support scripts, forms, reports directly
you will need something else (a front end if you will that has the user interface), and use a storage mechanism for the back end. whether SQL server is 'the' 'right' back end I dunno.
there's lots of competign products in the data storage world, from client server products to file server products. In the client server products include SQL Server, MySQL, POSTGRES, ORACLE and so on. some of these are limited versions, some are expensive un limited versions (most have limited use freebies).in the file server world theres several out ther includign SQLLite, Access/JET, Filemaker and the one that comes with OIpen office to name a few.
As to which one is right for your fathers requirements I dunno. given my experience (my bias if you prefer) I suspect that your father will be will served with something like Access or possibly Filemaker. whether he needs the power of a server backend I don't know.
migrating the tables to whatever new data store should be OK. as to what tools depedns on what you choose to store the data in. as you have a copy of paradox the easiest route (assuming your chosen back end doesn't support native paradox interaction may be to go through something like CSV.
as to migrating the scripts and forms, not a cat in hells chance, you will have to create these in the selected front end.
bear in mind you have the choice in creating your new front end as to whether you use
a conventional development environment such as
VB.NET, ASP.NET or wahtever
or a scripting language runnignon a server (the server could be the local machine) and use PHP, ASP.NET and so on
or a RAD tool such as Access or Filemaker.
bear in mind you do not have to use the inbuilt data storage mechanism in Access to use Access, its quite happy to talk to the outside world. however unless you are fully up to speed with server development in Access I wouldn't recommend using Access + a server for a first off project (unless you are prepared to dig deep into the internals of Access). whatever else people may say about Access, and a lot of people do say things about Access it has a very good report generator and can be very user friendly. however the user friendliness and RAD tend to take a back seat if you code an Access application to properly interact with a server product.
However its hard to give any useful advice as you don't really give a flavour of how big this application is, how many users, how secure must it be, what is the calibre and expertese of the developer.