If you stick to Western Digital, Seagate, Maxtor or Fujitsu you won't go far wrong.
The main thing is that HDDs are ridiculously cheap today and the larger the capacity the cheaper it works out per GB.
A 120GB drive can be priced as little as £56 and a 160GB at just £4 more. Even a 200GB version can be acquired for only £80. Six months or so ago these capacities would have been half those figures.
Most of these will be OEM (original equipment manufacturer) offerings, but a WD full retail version for instance would only be around £10 more if you needed the kit.
The 7200rpm figure is the spin speed and, obviously, superior performance to 5,400rpm - also look out for a cache of 8MB rather than 2MB; costs a little more but worth it.
Could be worth using one as your main drive and the 60GB you have now as a second or backup HDD.
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Scan of Bolton's TodayPage often has even better prices on occasion: click here