VMWare might use slightly more RAM, but not significantly. It will use a lot less CPU time, which is more useful

VMWare's minimum memory requirement is the amount of memory you want to give to the guest OS (say, 32MB for a small win98 system or a small linux) plus about 5-10% for various bookkeeping stuff (shadowed page tables, other horrible torturous hackery which is required because x86 is such a crock of shite for virtualisation), plus the size of VMware itself, and then maybe a bit spare

QEMU will use memory in a similar pattern - it still needs 32MB of ram at least if the guest OS is going to appear to have 32MB.. it might have a little less overhead (because it will, e.g. emulate the guest's MMU using the guest's own pagetables, instead of VMWare having to keep a shadow copy of them all so that the real hardware MMU can do it safely) but not a lot.
I've successfully run VMWare on my xbox under Gentoo, it works just fine and is certainly no *slower* than QEMU

If it uses over 64MB of ram to run DSL on your Windows machine, you'll probably find the virtual machine is configured to have.. yep, 64MB of ram

You can undoubtedly crank that way down if you're just firing up DSL and not doing anything complicated. (though, a much cooler and MUCH faster way to run Linux on Windows is to use
coLinux, which actually lets a full Linux kernel run natively on the hardware at the same time as the Windows kernel via *really* cunning device driver hackery. No emulation, no virtualisation, very fast indeed but still eats up RAM)