Hi SC and welcome!
Short answer: right click on your tables select table properties and make sure the cell padding is set to 0.
Longer answer ...
InfoPath uses XML which is great for the following reasons:
- Structured data that can be searched
- Client side validation using XML data schema, restrictions and other constraints
- Supports Web services integration without having to write code
- Industry standard format
To display the XML data on the screen, InfoPath uses XSLT to transform the XML into HTML.
This is far easier than embedding two-dimensional layout information in the form template since it relies on existing open standards (as opposed to proprietary conversion from two-dimensional coordinates to XML data and back again.
Two dimensional layout engines (like Adobe, etc.) do not natively support XML for the opposite reason - they were built using proprietary layout technology and so any XML support is an afterthought and not true, native, run-time support.
HTML can be used to create high fidelity views and web pages. Certainly, you can create tables that line up well - just remember to set all cell padding to 0 and you won't have embedded table messiness - everything will line up.