Rereading your first post, i see the problem.
It's very strange that GoBetwino tells you that your OO program has ended. If you started your OO program with a SPRID command type in GoBetwino it should not close after each "insert" with the Send keys command.
Unfortunately most of my stuff is in temporary storeage, while i'm looking for a new home, so i have very little to test with.
Are you using the full XL sample ?
Did you put the SPRID command in your Arduino Setup() where it should be ?
Because as far as i remember in the Arduino sample code i send some data to Excell, then close Excell and email the excell sheet ?
Could that be the problem ?
Which Windows version are you using ?
Also it should be possible to send data much faster than once every 5 seconds, but if the OO program is restarted every time then the speed slows down of course.
While testing GoBetwino i inserted integers in 3 cells, read with Analogread() from 3 potentiometers, and was able to do that serveral times a second, and it could probably have run faster.
That said, the way GoBewtino does this was never meant to run at rocket speed. After all you send your data over serial, each command has to be parsed by GoBetwino and the recieving program (Excell / OO) has to be put in the foreground, and first then are the data inserted.