The 'low memory' message is not related to the size of the memory card - it means the 'phone's working memory - it sounds like you may have too much running at once, or have put too much stuff directly onto your'phone (rather than the memory card). Try switching off and on again to kill any rogue processes or things you're not aware of still running, move all that you can to your memory card and try again. If the 'phone doesn't have enough free memory to run the installation program, it may explain the message you're getting....Windows errors don't always mean what they say...
Sorry if I'm teaching my granny to suck eggs here...
Crash
====
'I wouldn't recommend sex, drugs or insanity for everyone, but they've always worked for me.' - Hunter S. Thompson