[Neither a teacher nor a native speaker]
Just my two cents. Hope teachers or native speakers can really give you a hand.
1. There should be a colon after "Dear Sir/Madam". And I prefer replacing the slash with "or", that is "Dear Sir or Madam:"
2. If you don't know the name whom you write to, you should write "Yours faithfully" rather than "Yours sincerely".
3. You repeated your resume is attached. I think it would be more terse to mention it once.
I refer to the position of Junior IT Support Technician advertised at jobcentreplus.gov.uk on Oct 31st, 2008. Please find attached my Curriculum Vitae, the required information specified in your advertisement.4. I don't think you finish the last sentence in the paragraph as below:I am extremely excited about this opportunity it has a definite appeal for me, both on a personal and career basis. I enclose my resume for your review and look forward to meeting with you in the near future. Should you have any questions or require clarification on any information, please contact me at the above telephone number.
5. It seems to me that the construction of the sentence are not parallel. You mixed noun phrases and adjectives together.I am extremely IT orientated from ever since I was at secondary school and feel extremely comfortable using them for whatever the purpose. On top of this I am the main person from my friends and family who people turn to for advice or support. I feel if given the opportunity to fulfill the position you advertise you will not be let down and I am
I am very enthusiastic, energetic, a quick learner, excellent speaker, a good team player, highly motivated, very reliable and cooperative.
Student or Learner