My roommate wants to move out before our lease is up can i take her to court to make her pay the rest of the rent she owes on the lease?

Yes, assuming you have an acceleration clause in the lease which provides that, upon default, all the rent immediately becomes due and owing.  Otherwise you may have to sue her every month as the rent becomes due.  Also, in some jurisdictions (don't know about Oregon) you may have the legal obligation to try to mitigate your damages by renting to someone else.  In other words, lets say this woman is paying you $500 per month rent and has seven months to go, representing $3,500 damages to you (assuming you don't save any money because she has vacated, i.e. by paying less electricity or reduced cable bill or something similar).  You may be obligated to try to rent to someone else, and to reduce your claim by the amount you receive from the new tenant (less any monies you paid to get the new tenant, like money spent on advertising the space).  So if you rent to someone else for six months at $400 per month, the amount you can collect from the first tenant would be reduced by $2,400.