What is the maximum map size I can export to Pocket Streets? Seems to be about 5Mg.
And why is that the limit since much larger maps could be stored in newer PC's with 64Meg?

There is no disk space size limit in Pocket Streets. However, there is a size limit in the maximum number of "grids" per Pocket Streets map. In densely popoluated areas, these grids contain lot of data, so the file size there will be larger (I exported a map of New York City which was 9.3 MB).



Even though Pocket PCs can have lot of storage (especially if you add big CompactFlash memory cards), this doesn't necessarily mean a Pocket PC application can handle 64 MB files with acceptable performance. I assume this is why Microsoft has this (in my opinion fairly reasonable) grid size limitation in place.