asp questions before i begin project

hi everyone. building a website for a client and have a few questions
related to best practices, what i should use etc...

the site will use a database to store info entered by users. each visit will
allow the user to input no more than 2 fields: email address, and a comment
field. the site has the potential to become pretty busy so my first question
is, what should i use on the backend? a dedicated SQL server isnt an option
so im looking at either an Access database, or the desktop edition of SQL
installed on the web server.

second question (and this might help decide which DB to use) is: what are
the proper ways to open the databse so that multiple writes can be done at
the same time in the case where more than 1 user are entering info at the
same time? im referring to LockType, CursorType etc... (im not entirely sure
of the workings of these things so if someone could give me a quick opinion,
and point me in the right direction i can take it from there)

thank you in advance