I've got Parallels installed on an external hard disk since most of the software used in geology is for Windows. It works OK, but it's a little inconvenient carrying around an external HDD for the rare case I want to use Windows on a MacBook Air. I have a 128GB SSD, and somehow it's about full. So I've been looking into alternatives to run Windows. I could upgrade the SSD, but after killing my iMac's internal display adapter, I'm a little leery of fixing this computer. I thought about an SD card, but I don't think any of them are fast enough. The best option I found was a USB SSD, but those are over $100. For $30 right now I can get a SanDisk 64GB USB 3 flash stick with read and write speeds between the cheaper flash sticks and the SSD. So I wanted to see if anybody had experience with these. The hard disk I'm using externally is nothing special, 5400 rpm I believe. Thanks!