Shouldn't be any troubles, we routinely mix 64-bit and 32-bit TSVN clients at work, no problems. Maybe you'll need to make sure the server install is 32-bit (no idea if there's even a 64-bit SVN server), but the client makes no difference, it all gets committed the same way as far as I can tell.
I've been thinking about setting SVN up here at home for backup, on an older 32 bit machine that i'm not using. Problem is i'm running 64 bit xp here on my main system, and was wondering if anyone has had any problems getting setups like this to work? I couldn't manage to set up a network printer between xp32 and xp64…