Hi there,
I was in the exact same position as you; I have an original P180 and basically b/c it has no cable management (i.e. it's not a P182 with the cool factory mods) my case was a bit of a mess. You can clean up a P180 if you really try but even that still leaves a lot of cable clutter.
What I did was Google "P180 Mods" and I found literally a hundred threads w/pics. The ones I focused on were about basically turning a P180 into a P182.
If you have a Dremel and several hours of time you can make your own P182. The 24-pin ATX cable wont' route the same way due to the lack of a recessed mobo tray, but it's almost as good. I wish I saved the links! The most radical Dremeling occurs in back of the top hard drive cage.
Underneath that area where the useless little parts box mounts...you basically cut the floor out. You also cut out the side of the HD/PSU 120mm fan mount. You run your ATX cable to the side of the fan, thru the hole you cut in the floor where the cage mounts and voila, it's right there where you mobos 24-pin connector is.
I haven't taken any pics of mine yet.

Google and you'll find it.
I really like my P180; quiet and it holds a full-size videocard and 6 hard drives. It's also got filters, which are very important for me. I am not ready to replace it yet.
Good luck.