if you do any text in another programme i.e illustrator, although it is vector, when you export it, paste it, or import it form, into photoshop, it will rasterize it, ie. pixelate it. the best thing is to stay in photoshop, use a hi res. document and check the anti-alias box. provided the text is on its own layer, you may then run some filters to smooth it out even more. gussian blur it then unsharp mask a few times, just a little at a time it if you have just the original filters( not the best method ). there are a lot of 3rd party filters that smooth out jaggies and are very powerfull, but are costly and need to be hunted down. unsharp masking it in the k (black) channel will result in a cleaner ,crisper look.( if you are working in cmyk mode)