Should I invest $1000.00 in Sirius Satellite Radio or wait for the Visa IPO?

I have $1000.00 to invest. I already own 150 shares of Sirius. Should I buy more or wait a while for Visa to go public and invest all $1000.00 into them. I am kinda leaning towards Visa right now, but Sirius is looking very tempting with their merger with XM radio almost certain.