Maven may download, but it downloads to a disk-based cache. So regardless of what annoyance the downloading process may result in, simple downloading isn't sufficient to blow out RAM.
In order to actually run out of memory, you'd actually have to not only be downloading, you'd have to be actually attempting to use all those jars in the project being built.
There are ways to see what artifacts are being invited in for a given POM, although I'd have to google to remember what they are. The m2eclipse
IDE plugin can also show them in graphic displays, but being that you're running short on RAM and Eclipse is pretty memory-hungry itself, I'm not sure you'd enjoy that.
On the whole, however, I don't recommend specifying version ranges in POM dependencies. The whole point of versioning is that things
change between versions. If you give an explicit version in the POM, it may not retrieve the latest-and-greatest, but it will retrieve a version with specific behaviors as opposed to whatever can be grabbed. More importantly, if there are transitivity issues, you could certainly end up with cases of multiple versions being pulled in from the different secondary dependencies. I have a problem with a project right now where 2 different versions of a JAR are being tagged and I didn't even specify version ranges.