Also,
In regards to Opera memory saving measures, besides the other reg edit I mentioned, you can also change:
HKLM\Software\Opera\Info: "MemoryThresholdWanted" to "0". I believe this tells it that you don't want a Memory Threshold. I believe just this one regedit is enough to get rid of the memory error.
Aside from that you can also add this line to HKLM\Software\Opera\Prefs\User Prefs:
"Cache Directory4"=\Storage Card\Opera Cache
You can name your new Opera Cache folder whatever you want, that's just what I chose. Point being that it saves the cache to storage card rather than on the device in the normal "\Windows\Opera9\profile\cache" spot.
On that note, you can also use cleartemp and direct the custom folders to the opera cache spots on the phone and on your storage card.
Edit: I forgot to remind you that you will need to create the folder (Opera cache, or whatever you want to call it) on your storage card in order for the:
"Cache Directory4=\Storage Card\Opera Cache" registry edit to work.
I tried to adjust my Opera cab to this new registry setting and to create the folder on the storage card, but the cab won't install if there is no storage card inserted in the phone and so the phone never fully boots. While I always have my storage card inserted when I flash, I know that a lot of people don't. So including this regedit before hand in the ROM just won't work.
I did, however include the Memory threshold wanted = 0 in my Opera cab, and I've upped the no. of availabe tabs to 9 and the no. of avail history pages to 30.