You can run i386 Debian on your I3, but unless you have a specific reason for doing it, you are better off running the x86_64 version - its there are virtually no disadvantages to running the x86_64 version, but a number of advantages, including
- Easy support for more then 4 gigs of RAM (although i386 can do this also if you install a PAE kernel)
- Allows you to do more with virtual servers - KVM, for example, really needs to be installed on an X86_64 install
- x86 supports 386 programs, but the reverse is not true.
The 386 architecture is really around for very old PC's (This change occurred around the time of the Pentium 4 for most people)