The Pocket Streets 2005 (PS) docs states the following:
Installing Pocket Streets on a PC Card Is Not Supported
Installing Pocket Streets for Pocket PC on a PC card is not supported. You must run Pocket Streets from a folder on your mobile device. However, you can store maps on a PC card in the My Documents folder. Panning and zooming operations may be slower with maps stored on a PC card than with maps stored on your device.
This may make many people think "hey! I can't install the app on a memory card?"? Do I have to waste 450k precious RAM? That's not the case. You can even install the app on a CF/SD memory card which is in the PCMCIA (PC Card) sleeve in any iPAQ. That is, you can freely install your stuff anywhere. This stuff may have been written back in the WindowsCE 1.0 times (1997) when it was indeed impossible to execute applications from PCMCIA-based memory. Times have been changed – but the old stuff remained in the MS docs.
Some more stuff on PS:
First, you can freely remove the following help(-related) files from \Windows
(to free up 45k RAM):
06/14/2004 07:43 PM 1,248 CEArrows.bmp
06/16/2004 12:48 PM 43,749 pstreets.htm
06/14/2004 07:43 PM 130 pushpin.2bp
06/14/2004 07:43 PM 130 zoomin.2bp
06/14/2004 07:43 PM 130 zoomout.2bp
Second, you may want to "benchmark" a map to find out which of your memory cards/types is the fastest with PS. For example, on my Pocket Loox 720, scrolling around on a map is pretty sluggish from my 1 Gbyte SD card; considerably faster from my CF and the fastest from the File Store and the RAM. The difference is about twofold – not very annoying, but pretty visible.
Interestingly, the same SD card resulted in definitely faster operation on my old iPAQ 3660 (RAM-based operation was similarly faster than the same run on the Loox), put in the above-mentioned PCMCIA sleeve. Indeed, when massive-scrolling, even old QVGA devices can be better than even top-of-the-line VGA ones.