Well you probably have time to study so go ahead and do this.
Buy the Official Guide to the GMAT 11th edition and go over the questions (yellow book) and also get the green and purple books (Quantitative and Verbal versions) and go over the questions slowly.
But since you are tired after work you might want to get a princeton review
2007 book and use the CD to get yourself into studying. The key is to get excited about the test. I know this may sound hard, but this test can be conquered.
And by joining this site you have stepped a foot in the right direction. Keep up the good work.