Issue with slow network overwrite lifecycle?

I have an XP workstation running some webcam software which is saving a
small .jpg image every 1 second to a share on a 2003 server. The XP box has
an 802.11g connection to the rest of the network (and fwiw, has a continual
and consistant signal strength rating of 'excellent / 54mb'.) The 2003
server is my PDC and the XP workstation is a member of the domain w/
full-blown access to the share. The file that the XP box is saving to the
server is relatively tiny, a .jpg file on the order of 34-36k in size. It
is the only file in the share folder.

On the server, if I navigate to the source of this share and hit F5 several
times (to refresh the folder contents, and hit it every 1/2 second or so)
I'll see something like this (each line is me hitting F5 once):

(hit F5) folder contents = image.jpg 35k
(hit F5) folder contents = image.jpg 36k
(hit F5) folder contents = image.jpg 0k
(hit F5) folder contents = image.jpg 34k
(hit F5) folder contents = image.jpg 36k
(hit F5) folder contents = image.jpg 36k
(hit F5) folder contents = [empty]
(hit F5) folder contents = image.jpg 0k
(hit F5) folder contents = image.jpg 35k

These empty/0k occurances are creating a problem for a website running on
the server. It's trying to grab image.jpg at regular intervals and
sometimes, it fails. Come to find out it's failing when the file size is 0k
or, simply not there.

Now I can appreciate that (in theory) it would be possible to hit F5 and
catch the file mid-rewrite and see a partial size of 14k, or something like
that. But since hard drives do what they do so very quickly, and because
this file is so very small, it seems extrememly unlikely that I could
consistantly capture the file at exactly 0k so often as I can. Given hard
drive access times, this file is staying at 0k for a very long time - 1/2 to
1 full second.

My *guess* is that my 2003 server begins receiving the new copy of image.jpg
and does the following:
1. Kills the existing one
2. Creates a new one (a "placeholder" with 0k size) of the same name.
3. Sits and waits for the file to arrive, probably dumping chunks into the
placeholder periodically.
4. Continues until the file is completely rewritten.

I dunno if this is an accurate description of what's really going on (is
it?); what I'd rather have it do is leave the existing file alone while it
waits for the complete delivery of the new file from the XP box, and _then_
do it's overwrite routine once the file has completely arrived to the
server. That way, the file rewrite process should be much much faster...?
Is there any way to tweak this at all on either the server or the xp box?