Depends on what you're going to uni for. If you're going to use the laptop for scientific projects or for computing, you're not going to use Windows anyway, and you're probably going to use GNU/Linux. In that case, there is no benefit in getting the latest and greatest hardware at all, because on a computing platform like linux, and contrary to a media consumption consumer platform like Windows, the latency in evolution of hardware support is really apparent, so you'll be better off with a 6-12 months old laptop than with a latest model one, because you won't be able to really use the benefit of the newer hardware in terms of computing efficiency, and you might even experience some bugginess that you would only expect from a closed source system, as the quality standards are much lower there than for open source software. For instance, you won't be able to really use all the benefits of the Intel Haswell platform until linux kernel 3.11, which isn't officially released yet, or even 3.12 as far as some graphics functions are concerned, which will not be released in the next 6 months. Intel graphics work very well with linux, and for a non-gaming laptop or even a moderate gaming laptop, there is no real benefit in investing in dedicated graphics solutions when you're going to use GNU/Linux.
I would always advise getting a used laptop with a bit more screen resolution and a lot of connectivity options, over a brand new lower grade one, because you'll basically never be satisfied with the lower grade one, and you'll buy another one anyway, and that's throwing away money.
I would also always advise getting an Asus laptop from the mid- or high-end ranges, and especially the N series laptops are a good compromise, they have pretty fast hardware, pretty good build quality and serviceability in comparison to anything else except expensive pro grade laptops from dell, lenovo, sony and toshiba, and very good connectivity (hdmi out for second screen, esata, pci express, a lot of usb ports, optical drive, standard LAN-connector), with a decent resolution screen, a good battery, and a more solid feeling keyboard that's suitable for a lot of typing. New they cost about 800-900 USD, nearly new or in a student promo you can get them for 500-600 USD, a one year old used one in very good condition costs less than 500 USD. Ask your local Asus distributor if there are any refurbs available, Asus sends info on refurbs to their customers directly, and doesn't publish it on their website, so you'll have to call the distributor or Asus themselves to find out if there is anything available. I have bought several of these over the years, and they are just like new products, come with a warranty, and have been thoroughly factory cleaned and wiped. If you're going to use GNU/Linux - which is highly probable in uni - Asus laptops are a good choice because Asus submits the keybindings of their hardware keys (volume controls, brightness controls, wifi switch etc), and they work out of the box with the linux kernel, without the need of special drivers or config work, and the Asus proprietary hardware power management system is also supported by the linux kernel natively.
If you find an Asus N series 17" laptop, you'll have dual drive bays, so you could use a large capacity mechanical HDD for storage and a fast SSD for the operating system internally, and you'll have a slightly larger and more comfortable keyboard and a higher resolution screen, but it will be slightly less portable.