How do you access a field from a user object

I'm just starting to work in Drupal and have no experience with objects.

I'm using :

$user = user_load(array('name' => $someUid));

Then trying to compare a value in the object table to a value in an array read from a csv file, like this:

    if ($user['aspe_firstname'] <> $UserRecord[$FirstNameNum]){
			$RecordUpdated = True;
			$new_user['aspe_firstname'] = $UserRecord[$FirstName];
		}

$FirstNameNum is a number, $FirstNameNum = 5

The program dies when it hits the if. How can I do this compare?

I'm also fairly new to arrays.

Thanks Rich