From the look of it, yes it sounds like an overkill. If you are on windows, you would be hosting on ntfs filesystem backed by an appropriate raid level for disks. That is good enough to manage a Database of your size.
ASM - is it overkill for a small database
From: "Schauss, R. Peter (IT Solutions)"
Date: 30-06-2009 19:23
I am in the very early planning stages for a small database (Oracle
10g), probably no larger than 10 gb/200 users, probably running on a
Windows server. Would it make sense to use ASM or is it overkill for an
instance of this size?