We cannot answer this for you. You need to determine this based on SLA etc. I suggest you read the
chapters about backup and restore in Books Online. Be prepared to spend at least a day to understand
these topics. Based on that you decide with whoever own your system what types of backup you
require. IT all boils down to how much data loss you can tolerate.

Pressing the "schedule" button in the EM backup dialog creates a new SQL Server Agent how. Check out
your jobs, if you selected this several times you probably have lots of Agent Jobs that do backup.

... also you might want to check out the maintenance plans. These has options to keep x generations
of backups and clean up old backup files etc.

Backup and recovery procedures should be defined based on your RPO/RTO. You
can have a combination of FULL, Differential, Filegroup and transaction log
backups in SQL Server 2000.  But then, again, these will only make sense if
you define your RPO/RTO

Depending on how critical your database(s) are to your business, you should
consider engaging a consultant to help you set up your backup and disaster
recovery plans.  I realize this can be an expense you haven't planned for,
but if you are new to all this, it can be, IMO, well worth it.  If you don't
have experience in this area, it is easy to have an inadquate
backup/disaster recovery plan.  And the problem with that is you often don't
know what you are doing is inadquate until you need to do a restoration, and
then it's too late.

It's hard for a newsgroup to give you answers on this since it depends so
much on what you are doing with your database(s) and how important they are
to your company.  What you need to be doing may well depend on information
that is confidential to your business and that you can't be posting on a
public newsgroup.  On the other hand, a consultant who knows how to do this
may well be able to do this fairly inexpensively and quickly.

Tom

To add to the comments, you should either back up the transactin log OR set
the database recovery model to SIMPLE.

Otherwise, your transaction log will grow w/o bounds and you'll be back here
in 6 months asking how to shrink it or worse, back here saying, "well it
grew to big, so I found a random web page that suggested deleting it and
letting SQL Server create a new one and now my database is hosed."

HOWEVER, before making the decision between backups or SIMPLE mode, PLEASE
make sure to read all the other comments posted.  WHY you might decide one
over the other is a critical decision; as is how often you back up the
transaction log.  Some places do it once a day, others 4 or more times an
hour.