The metro system will probably be the best choice for transportation to/from the hotel and conference center. The conference center is across the street from the Virginia Square Metro Station and the hotel is near the Rosslyn Metro Station, one stop away.
From the conference center: take the Orange line (towards New Carrollton) and get off at the Rosslyn Metro Station. The fare is $1.35 (don't forget your receipt for reimbursement).
From the Hyatt Arlington: take the Orange Line (towards Vienna) and get off at the Virginia Square Metro Station (about 6 minutes). The fare is $1.35 (don't forget your receipt for reimbursement).
Here's a link to help you plan your metro travel:
http://www.wmata.com/
Directions to conference center, parking information, etc. can be found
here:
http://www.cs.virginia.edu/~secdep/SoD/Directions%20with%20hotels%20and%20parking1.pdf