I don't know the difference between the ExpressCard 54 types, but have an M90 and want to dedicate the slot for a Compact Flash reader. Does the M90 use PCL or PCLe and is there any real difference between these two? I use 16GB UDMA Compact Flash for my camera (currently use SanDisk Extreme IV 45 MB/s). I'd of course prefer the faster reader if it'll work in my M90, as CF cards keep getting faster. A downside to the first card is it isn't available in US directly, but can be had off eBay.

This option is the PCLe:
http://www.datafab.com/product/p2express_CF_PCIe.asp
http://cgi.ebay.com/ws/eBayISAPI.dll...fvi%3D1&_rdc=1

This one is slower PCl:
http://www.datafab.com/product/p2express_CF.asp
http://www.amazon.com/DATAFAB-Expres...pr_product_top


Here's another, but gets some mixed reviews on fit & function.
http://www.bhphotovideo.com/c/produc...pactFlash.html
http://www.amazon.com/gp/product/B00...pf_rd_i=507846

From what I understand you can use any Express card 34 and 54 mm in size using a 26 pin i/f.

So as long as your buying a adaptor that works with your compact flash card you should be OK

this is from dells site

http://support.dell.com/support/edoc....htm#wp1082940