www.PCsecuritySoftware.com
Way too long, should be something like pcsecure.com, more consumer friendly. You can be literal, but you can't be too long for such products.
www.CorporateLease.com
How do you brand this? Corporate leasing may be a generic term, just like Corporate Financing. Good for redirect perhaps. But lacks any punch.
www.ConversionCalculator.com
Way too broad. forexconversion.com is much better if you are looking in this area. But then again, this is standard stuff on most web-sites that need this feature.
www.ConsultancyFirm.com
Again way too broad. The internet is now all about niches. And you want a name to reflect that niche. You could use it as a portal, but then again, be careful of being too anal.
When you buy names in future, look for the following imo;
1. Targeted meanings that companies can live up to, not hi my name is God.
2. Things that people want and need, not descriptive terms for things that are taken for granted, eg. air.com (unless you are Nike)
3. Punchy names, and punchy names normally don't exceed two words at the best of times. A ten word domain name is fine if you are willing to spend mega bucks to promote it, but don't expect great resale value.
Having said that, your names are still good if you MANAGE to find a developer with specific needs.