The installation of SQL Server is a no brainer, for the most part. Any dba should also know by now that dbs should NOT be installed on the system drive (typically C:) and if you're really going all out on a major production system, dbs and trans logs should be on separate drives as well, where the logs drive has better performance.
Now, I've installed SQL at least a half a gazillion times since 1998 and I typically go through each screen with a fine tooth comb, especially on a cluster. However, if I haven't installed it in a while there is sometimes a gotcha that requires me to uninstall SQL and install it again. This post is just as much a reminder for myself (& punishment for forgetting) as it is for anyone reading it.
In the newer versions of SQL, when you get to the screen that asks which components you want to install and the drive location, each component has it's own drive location. So, when you set the drive location below, you're only setting it for that specific component that is highlighted. Therefore, you need to highlight each component and change the drive location. This is also true even if you set the drive location at the parent component level.
Got it self? Good. If I forget again, I'll come back and add screenshots or something for more punishment to myself.
I am aware there are ways to move the system dbs and such, but it's no picnic (unless you mean Problem In Chair Not In Computer) and definitely not worth it if you haven't done much work on the SQL server yet. Do it right the first time or uninstall and do it over, if you can.
Ok, hope this is helpful to someone, my uninstall should be done, time to go back and do it right...
P.S. Don't forget to delete all the files SQL leaves laying around after the uninstall. It won't affect the new install, but it could lead to confusion in the future and is just overall better administration.