Ah... just checked with Process Explorer and USBDLM is using 2620 K Private Bytes. VM in Task Manager is roughly equivalent to Private Bytes in USBDLM.

I'm simple:  usb disk ejector does what I need:
http://quick.mixnmojo.com/usb-disk-ejector-120-beta

Simply provides me with a list of usb devices (and volume names) that, with 1 click, I can eject.  It's beta, but does what I need it to do.

So many times, after using many different USB drives (HDs, USB sticks...), windows gets all mixed up and starts assigning unusual letters to my drive, which makes backuping, errrrrr, an interesting experience.

Well, this depends on which software you are using for backup. I use SyncBackSE, and do not have to bother renaming USB device letters. This is because you can use your USB device's label name. Labels can be set once for all for a USB device very easily in Windows and other operating systems, I guess.

To refer to the USB device called my_device, you just use this instruction:

%LABEL=my_device%

To access to folder1 on your USB device, you just use this instruction
%LABEL=my_device%folder1\

No matter if the letter is G:\ of F:\ of K:\

You can also use serial numbers directly in your backup profiles. Details here:
http://www.2brightsparks.com/help/index.php?action=kb&article=11

USBDLM New Beta is out with interesting new features:
V4.2.9.25 beta (26th September 2008)

    * New: In sections [OnArrival], OnRemoval etc up to 10 commands can be executed (open1 to open9 and the known open)
    * New: [OnArrival] for TrueCrypt volumes
    * New: When a DeviceID is configured then the BusType can be omitted for non USB drives, same for the DriveType e.g. for CDROM drives
    * New: [OnArrival] can start a program under Vista with full rights ("elevated")
    * New: Criteria "UserIsAdmin" is under Vista related to the "elevated" user, so it is 1 for an Admin under UAC
    * New: [OnRemovalFailed] is executed asynchronousely to avoid event ping pong when using RemoveDrive
    * New: AutoRun on System Events
    * New: NoMediaNoLetter more reliable under Windows 2000
    * New: First time arrivals under Windows 2000 optimized
    * New: Using [OnArrival], [OnRemoval] etc there is the new default criterion MinVolumeSize=1, so a media must be present
    * New: Drive letters can be checked [on resume] from standby and hibernation mode
    * New: Drive letters by Volume Serial Number