Yup, xilinx download section generates vacuum on a specific region on genus Equus africanus asinus. I always end up doing the login dance, clicking the download, and then grabbing the 302 redirect. Then download that url using wget with reget. Because less vacuum.
And yeah, to get just Impact you still have to grab a whopping 1 Gb download. Silly people.
Anyways, if this is still a problem send a PM for a direct link.