External Hard Drive

I don't know if this is in the right place. I'm a recently converted Ubuntu user. I switched over because of wireless on my laptop. Props to Mepis for making it simple!!

In fact I have my laptop almost exactly the way I want it, with one exception. I have a 200GB external hard drive that I would love to use for backing up my files and such, but it's formatted as an NTFS. Now this ordinarily wouldn't be much of a problem if my life was Linux only - I'd just reformat it to ext3. However, I also have two Windows workstations which I frequent and I don't want to mess with the utility required for connecting ext3s in Windows (mostly b/c it keeps changing the drive letters of the external hard drive and any other usb media I insert - like sticks... not during my session, but between them... so my stick which is F today might be R tomorrow.... It's quite annoying)...

Anyway, the long and short of my question is: how can I mount my ntfs external read/write in Mepis Linux. I know Mepis comes with the ntfs-3g preinstalled, but I don't know how to use it... I also don't know if it's ok to use fstab b/c the external isn't always connected to my laptop... Most of the information online I've found regarding this has been about accessing the windows partition on a dual boot machine, which I do not have (my laptop is 100% Linux)...

Any help? Thanks in advance