WEP or WPA connection through a Ubuntu phone hotspot???

I have set up the 'Hotspot' on my Aquarius 4.5 Ubuntu edition, and most of the time it is totally brilliant. For testing purposes I have had several Ubuntu-based laptops, a Windows VISTA laptop, and an Android-based 'tablet' connecting through it fully successfully. But the one machine that I REALLY want to connect through it is an ancient Windows XP laptop - and it won't! The problem is that the Windows machine will only connect to a WEP or WPA network, but the phone only seems to offer a WPA2 network. Is there any way for the UBUNTU hotspot to offer a WEP or WPA connection?

[You might ask 'why am I faffing around with an old XP machine?' The answer - It runs some essential software that cannot be persuaded to run under UBUNTU through Wine, but it needs to have Internet access from a remote location. The Ubuntu Phone hotspot appeared to be the perfect solution - except it isn't!]