The PS3 cable, and the Sony AV (HD30P) cable are both 3 metre, certified HDMI 1.3 cables.
There won't be a jot of difference really with that cable over the PS3 one, other than it making your wallet being considerably lighter. Save your pennies, honestly. Your DVD player was £90 so there's no point in spending £40 on a cable, especially when it's a digital one.
Have a look over at AVForums if you don't believe me. There's people hooking up £3000 projectors to £1000 Blu-Ray players with cables that cost under a tenner. I have a 55" 1080p TV, and have my PS3 hooked up with a £7.99 HDMI and it runs 1080p just fine. My Sky HD box uses the freebie one that it comes with, which is probably worth £5, if you're lucky.
You only really need to spend more on an HDMI if you need a long run. Or, if you're transmitting high bandwidth uncompressed HD audio formats, then I suppose it could be considered worthwhile for peace of mind. But not for hooking up a DVD player to a TV.
But, if you simply must buy the Sony (HD30P) it's available on Play for £5 less at £34.99, and if you don't need 3m, shorter lengths are cheaper too