OK, but this still doesn't sound very Windows 7 - ish.
According to HP, your dv9700 has two RAM slots, for PC2-5300 (DDR2) SODIMMs. The largest stick it supports is 2GB, and the maximum total memory is 4GB. (Some systems don't permit you to fill every slot with the largest supported stick, but that's not a problem here.)
I doubt that going from 3GB to 4 is a worthwhile upgrade. If you decide to do it anyway, see here, for example:
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(I'm not sure that this is your exact model, but it may not matter.) The good news is that a 4GB kit costs about $56. The PC2-6400 are also listed as compatible, although they will probably run at PC2-5300 frequencies.
4GB SODIMMs exist, but they aren't listed as compatible, and they are much more expensive (hundreds of dollars for an 8GB kit).
If you want 4GB or more of RAM, I suggest a web search on the limitations of 32 bit Windows operating systems. (The short answer is that you'd need a 64 bit OS to fully use 4GB or more of RAM.) You may need a different laptop PC to install more than 4GB, regardless. The fastest Intel CPU that I see in the manual for your system is a Core2 Duo T770, which is 64 bit capable. (On the other hand, it's listed at 2.4 GHz. You wrote 2.6 GHz. What've you got?)