With Inkscape, it's the RAM that matters. The more RAM the better. From what I can tell, you have a little under 2 gb, on the "new" machine. I would call that a minimum system requirement. Although for the life of me, I've never found any system requirements published for Inkscape!! But my experience is that's a fair minimum. Of course Inkscape will work with less. But the lower you go, the slower Inkscape will work.
If you don't plan to work on large images (over 1 or 2 mb) you'll probablly be fine with that computer, for awhile. And in the next major version release (0.49) we'll have a new renderer which may help you to get by with 2 gb RAM. It will address many performance issues that we see....well, all the time
I'm not very well versed about computer hardware. But it doesn't seem to matter much what kind of graphics card you have (surprisingly to me). It's really the RAM first, operating system 2nd, and processor 3rd, that's my impression of what Inkscape needs. Although note again that I'm no pro

Maybe you could use that computer for awhile, and see how it goes? I'm not sure what you mean by "patterns". In some ways that I think of a pattern, you could get into trouble pretty quick with Inkscape's performance. But in other ways, maybe it won't matter much?
If you do go for a new computer, I'd say look for at least 4 gb RAM these days, and multiple processors wouldn't hurt. Also, a more current operating system. Windows 8 just came out, so you....well, I was going to say that you probably won't find a used one, but who knows, I guess. I have Windows 7 and it still seems new to me, so I'm happy with it. I'm hoping to hold out until Win9 (or whatever they might call it) before I upgrade again. Anyway, the next older is Windows Vista, which may still be supported by MS, I'm not sure about that, just guessing.
Until you decide what to do, here is a topic with tips on avoiding performance issues. If you find Inkscape takes a long time to do what you ask, these might help you get by.
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