At this state of your career, I'd say becoming a dba/sqldev is a good choice. You'll need to know basic Windows administration.
Most importantly: LEARN ABOUT PERFORMANCE MONITORING!!! I can't stress this enough. Probably only about 2% of sysadmins know about the correct use of perfmon and other tools. Learn it, live it, love it. It is the difference between a good admin and a great one. You can troubleshoot weird issues about 20x faster if you know tools like this.
You're also on the right track about learning about RAID and disk performance. All about spindles, LUNs, etc. Soak up that knowledge. Buy the SAN guys donuts for them to show you how and why they set up LUNs and RAID groups for your servers.
Then definitely keep going down the track of the certifications for SQL.