The launch date of the ATi X800 is planned for the 4th of May according to The Inquirer. It will be launched during the SBS event. They also heard that ATi claims it will be able to ship this card at the same day of launch, and that there are already quite some samples ready.
The R420PRO will be called X800PRO and will be clocked at 475MHz with memory clocked at 900MHz.
Everything is packed into 180 millions of transistors and the card has 12 pipelines as we suggested. The R420XT, Radeon X800XT will be higher clocked card with 16 pipelines which came as a huge surprise to us.
This card is meant to fight Geforce 6800 non Ultra - the one with 12 pipelines and should be in retail as soon as ATI launches it.
This means that you should be able to buy one on the 4th of May but let's wait and see if ATI can deliver on that day.
Faster Radeon X800XT will come just after E3, and soon after the 14th of May we are told. I cannot remember if I said this before, but the R420 is chip based on R300 marchitecture and you can clearly see this from its 96 bit precision support and lack of PS 3.0.
Performance wise it will give NV40 a good run for its money.