How big datafile is good for 400G's data?

I only has a PC server.  This PC server is running on a hard disk. This disk has 1000G space.

I installed Redhat EL6.2 x86_64 at this PC server. I also installed a Oracle11g R2 at this Redhat server.

Now I need to set up a schema. This schema should contain about 400G's data.  (A third party system will import 400G's data to this schema)

So I set up a tablespace for this schema.

But how to make datafile to this tablespace?

If I make a datafile 1G, then I have to make 400 data files to this tablespace. I don't think it's good to have so many data file.