50 high quality one-way backlink in forum

I am running an antivirus software coupon site. I would like the following to be done: Answer questions on good reputation forums sush as [login to view URL], [login to view URL], the home page of backlink should be at least PR4, when you answer the questions, you can refer to my perticular site URL or put my site url as the signature, I will provide you the anchor text and links. Totoally 50 postings, budget $50. if your answer is so good that is picked as the best answer(in [login to view URL], not all the sites has this features) or it is set to sticky in forum, then I will count this as 2 postings, i.e, one posting counts as 2 postings. 1. Your answer should be meaningfully, relevant and answer the posting's question, no spamming, just saying something like "this is a great posting, I really appreciate this or benifit from this" does not count. 2. Target US, english site. 3. Backlink pages must relate to computer area: hardware or software. 4. Domains must be from different IP addresses and different Class-C IP addresses, i.e. you should not post 2 links in the same forum. if you are doing good, we can do this project again after couple months. 5. No more than 7 posting per day. 6. Prefer authoritative domains (.com/.net/.biz/.org/.us/.gov/.edu/) 7. ALL links must be DO-follow. I will setup 50% escrow when you accept the project, after you finish the work and I have verified it, I will release the 50% escrow, then setup another 50% escrow, I will release the escrow when the links show up using Yahoo Site Explorer, Thanks -David