Do we have a wallet that will hold siafunds yet?

I am on version 3.3 still (havent opened it for a few months)

v0.5.0 has support for siafunds in the GUI

Is there a particular process for me to upgrade?

I would hang on for a couple of days until the official 0.5.0 version is released. The available version is a Release Candidate that is rather buggy.

thanks, I'm waiting for this, I have an old client also

Uh... That happened already. Version 0.5.0 released a day after the post you quoted and a day later Version 0.5.1 was released.

https://github.com/NebulousLabs/Sia/releases/tag/v0.5.0-beta
https://github.com/NebulousLabs/Sia/releases/tag/v0.5.1-beta