SQL install paths for 2008 R2

It's a system which could grow but at the start the load wont be that high.

I'm just deciding if there is any reason why I would not want to group user logs and temp DB logs into the same partition and likewise for the user database and TempDB.

I personally can't think of a reason why you shouldn't.

With regards to growth and loadl this is a complex assessment to decide immediately. However, these things can be changed later so don't worry as nothing is st in stone and you probably won't get it dead on straight away anyway.

Thanks!

I agree.  If it helps, a deciding factor for separating logs/data and, similarly, system databases from user ones is separate drive spindles and controllers.  If you have one set of physical drives partitioned into multiple volumes (logical drives), there really is not a difference in splitting up the data because you have not increased I/O capabilities in any way.  With multiple controllers, splitting up data files allows you to segment I/O of log away from data, system away from user, et cetera.

As stated, you likely will not guess right upfront, but do try to establish an initial size for tempDB and your databases that makes sense in a longer term.  In addition, take care with setting the file growth to something that will make sense as your data and usage grows.  In other words, growing a database in 1MB increments rarely makes sense in production.