i would say you should probably get a myname.com instead of myname.wordpress.com and a piece of advice for you if you are opening a tech blog i would say you get a domain address for the keyword you are going tto use instead of your name. for example- makemoneyonlineeasily.us.to is a good option because my keyword is make money online vishalnair.com wont be much seo friendly and you have a better chance to rank top with the first one
ok another related quesion say mydomain.com is populer, ex. pr4 / alexa 1k now i attached a blog to it blog.mydomain.com with diffrent contnet than mydomain.com is this a good idea? will my blog get higher position like mydomain.com do?
having a sub-domain will help you in better SERP for main domain if you have optimized sub-domain properly and have lined it to main domain.
Just wanted to point out that you may also want to have it on your own hosting account. The name.wordpress.com would be hosted on the wordpress.com website and this can have both positive and negative reproductions. For instance, using the WordPress.com hosting environment would automatically give you some PR, however, the data would be on their servers and may be difficult to take if you ever needed to move it to your own server or use a different blogging application. Using your own hosting plan would give you more control of settings, features and plug-ins. It would also be a better branding tool long-term. I would set it up on your own web hosting account. Best of luck.
Establish your blog on yourname.com. Link a main keyword that you are trying to target (or the name of your site) on yourname.wordpress.com. You don't have to choose just one but yourname.com is def the right choice if you have your own hosting.