Hi binz,
Practice CAT scores are only as realistic as YOU make the process of taking the CAT. The more the 'CAT-taking event' deviates from what you'll face on Test Day, the more likely the score is to be inaccurate (and in most cases, that means "inflated").
Here are some details to consider: When you took this CAT...
1) Did you take the ENTIRE CAT (including the Essay and IR sections)?
2) Did you take it at home?
3) Did you take it at the same time of day as your Official GMAT?
4) Did you do ANYTHING during this CAT that you couldn't do on Test Day (pause the CAT, listen to music, etc.)?
All things being equal, a 590 is a strong 'baseline' score (the average score on the Official GMAT hovers around 540-550 most years). Whether you can improve upon this score or not will depend on how you study, how much time you can commit to the process and the resources that you use.
What is your goal score?
When are you planning to apply to Business School?
GMAT assassins aren't born, they're made,
Rich