Well, I don't know what Dreamweaver is like for resource use, but NOF runs resonably quickly and smoothly on my Athlon XP desktop; I'm not sure that I would expect a Sempron to be quite as capable. I may be wrong, but I think the Semprons are pretty basic.
Of more concern would the possibility (or not) of playing games. Budget laptops with slow processors, modest RAM and integrated GPUs that share system RAM (and actually reserve a fixed part of it permanently) are not at all coducive to games. Every game is different though, so your choice may run okay.
Could you have this laptop demo'd to you before you buy?