What was the first part? 

Red Dead Revolver, but it wasnt Rockstar who made it. they bought the IP rights then made red dead redemption. while its technicially the second game in the franchise, you can say its theoratically a new IP, since the game took a new direction, dev and goal with RDR. 

Was that on the ps2? And is it any good? 

From what I heard it was ok, but not as good as most of Rockstar's other games in the last 15 years or so. It's sales were pretty lackluster considering the fact that it was a Rockstar game, in the 6 years between it's release and Redemption's release it sold less than 1m. It's surprising that Redemption was made after Revolver's lackluster sales, but it all worked out in the end for Rockstar, since Redemption became their best-selling game outside of the GTA series.

It was originally in development at Capcom, but development switched over to Rockstar San Diego who finished the game. Rockstar published the game in NA and EU, Capcom in JP. With Rockstar publishing and marketing it in the west less than 1m in sales was pretty bad, which is why I say it is pretty suprising that a sequel was made. In comparison to Rockstar's other non-GTA games in the last 10 or so years, Bully has sold about 3m (more with digital included from the 360 version), Max Payne 3 has sold over 4m, LA Noire has sold over 6m, and Red Dead Redemption has sold over 12m.