How Much Storage Do You Need in your Windows Phone 7?

My last survey seemed to court some controversy because people wanted it to ask the question of why someone needed removable storage; I simply wanted to know if people basically bought a storage card and left it in the phone for long periods of time - taking it out only to upgrade to a bigger card - or if they needed to take it out regularly to achieve certain functionality/scenarios. This question is similarly focused: if you're planning on buying a Windows Phone 7, how much storage do you need/want in your phone?